Keywords
epithelial ovarian cancer - follicle-stimulating hormone - dehydroepiandrosterone-sulfate
Introduction
Ovarian cancer is the leading cause of death from gynecological neoplasms and is considered
the second most common malignancy of the female reproductive system.[1] In India, epithelial ovarian cancer (EOC) alone is responsible for 5.9% of all cancers,
being more prevalent in the age group of 35 to 45 years.[2]
[3] Regardless of attainment in its surgical and systemic handling, the 5-year survival
rate remains low.[1] This is a source of concern for the Indian health care system; adequate management
is required to optimize patient care. First, however, it is essential to identify
the early markers involved in the pathophysiological process of EOC to prevent complications
and to initiate early management.
The low survival rate of ovarian malignancies can be attributed to many factors, including
the absence of suitable screening tests, nonspecific symptoms, and long symptom-less
periods, and the biological mechanisms accountable for its development/progression
are not clear. Although heritability accounts for 5 to 10% of all cases,[4] but by and large, the etiology of ovarian carcinogenesis is not conclusive enough.
Based on the animal experiments,[5]
[6] cell culture studies,[7] and epidemiological observations, it is hypothesized that endogenous hormones of
adrenal and ovarian origin play a significant role in ovarian tumorigenesis through
controlling cellular proliferation, differentiation, and apoptotic rates.[8]
[9]
Incessant ovulation hypothesis and gonadotropin hypothesis have been proposed for
the pathogenesis of ovarian cancer, with former postulating that the risk of EOC surges
with the numeral of ovulatory cycles because of amplified contact of the disturbed
epithelium of the ruptured follicles to mitotic stimuli and recurrent repair.[10]
[11] In humans, epidemiologic evidence in support of the ovulation hypothesis are the
observations that multiple pregnancies, breastfeeding, hormone replacement therapy
(HRT), and the use of oral contraceptives pills (OCPs) seem to have a protective effect
by decreasing the synthesis and secretion of follicle-stimulating hormone (FSH) and
luteinizing hormone (LH) through gonadotropin-releasing hormone (GnRH) signals.[12] The gonadotropin hypothesis proposes that increased serum levels of androgens (predominantly
dehydroepiandrosterone) induced by elevated gonadotropins stimulate increased proliferation
and malignant alteration of the ovarian epithelium entombed within inclusion cysts.
The observations substantiate that ovarian carcinogenesis is more frequent in women
suffering from a polycystic ovarian syndrome where LH levels are constantly increasing.[13] In vitro and in vivo studies have also suggested that circulating testosterone levels
can directly increase ovarian cancer cell proliferation through androgen receptor
signaling,[6] and other androgens-like dehydroepiandrosterone-sulfates (DHEA-S) indirectly affect
risk via conversion to testosterone.[14]
In divergence, few studies[15]
[16] did not support the original proposition and reported an inverse association between
androgens of adrenal and ovarian origin with ovarian cancer. Additionally, reducing
elevated serum gonadotropins by GnRH agonists, antiandrogens, or antiestrogens in
ovarian cancer patients did not prevent recurrence or lead to growth restriction.[17]
[18]
[19] All these findings advocate that reproductive history influences the risk of ovarian
cancer, that is, endogenous hormones have an etiologic role in ovarian cancer. Moreover,
endogenous hormone levels cannot be changed easily, unlike exogenous factors. Thus,
it becomes much more necessary to detect its association with ovarian carcinogenesis.
However, there is a paucity of information about concentrations of endogenous hormones
in the occurrence of EOC, specifically in the Indian population. Thus, in the present
study, an attempt has been made to investigate the role of prediagnostic circulating
concentrations of FSH, LH, and androgens (e.g., testosterone, DHEA-S) with the risk
of EOC using a case–control approach.
Materials and Methods
Ethical Consideration
The study was conducted under the ethical guidelines of the Declaration of Helsinki
(1964) and its later amendments on biomedical research on humans and was approved
by the Institutional Human Research Ethical Committee. Informed consent was obtained
from each participant following a study protocol after providing a detailed study
overview.
Participants and Study Protocol
This case-control study was conducted in the Department of Biochemistry and Obstetrics
and Gynecology of Maulana Azad Medical College and associated Lok Nayak Hospital,
Delhi, India. The participants recruited for the present study were based on a consecutive
sampling technique. That is, all the participants who fulfilled the inclusion and
exclusion criteria were included, ensuring that 1:1 matching was done. The study included
a total of 200 participants (100 newly diagnosed EOC patients and 100 healthy controls).
Participant Selection
Patients presenting with plausible symptoms of ovarian cancers reminiscent of pelvic
pain, abdominal swelling, bloating, emesis, anorexia, bleeding after sexual intercourse,
irregular menstruation, and pain were considered apparent case participants.[20] Prediagnostic venous sampling was done from all these plausible patients. After
histopathological confirmation for EOC, the patients were finally enrolled for the
study. Thus, patients with newly diagnosed, histopathologically confirmed EOC were
included in this study. Patients with cancers other than EOC, metastasized cancers
from other organs, and benign ovarian lesions were excluded. Other criteria for exclusion
were patients with any severe illness, impairment of speech, hearing, vision, or cognition,
or any significant medical illnesses that prevented participants from adhering to
the protocol, lack of approval by a physician, and patients showing disinterest or
refusal to sign the consent form.
Healthy controls were selected randomly from the outpatient department who visited
the hospital for routine health check-ups and were not suffering from any acute or
chronic disease nor taking any drugs believed to affect the physiological processes.
Participants with regular menstrual periods and had undergone hysterectomy with at
least one ovary preserved were included in the premenopausal group. Participants with
cessation of the menstrual period since 1 year along with FSH level greater than 40.0 IU/L
(physiological menopause) and undergone hysterectomy with bilateral oophorectomy were
included in the menopausal group.[21]
Participants' Examination and Measurements
A detailed present and past history of each participant were recorded, including name,
address, occupation, economic status, age, age at menarche, age at full-term pregnancy,
age at menopause, parity, phase of menstrual cycle at the time of blood collection,
menopausal status, duration of menopause, use of OCP, use of HRT, nutritional and
personal habits, education, medication, and history suggestive of any systemic illness.
Age was defined as the age at the time of the interview (though no documentary proof
had been entertained).
Sample Collection and Analysis
Venous sampling was done from all participants for biochemical determinations; however,
samples of only histopathologically confirmed EOC cases and healthy controls were
selected for further biochemical analysis. FSH, LH, testosterone, and DHEA-S were
measured on Roche–Elecsys 2010 (Germany) analyzer based on the principle of electrochemiluminescence
immunoassay. Each pair of cases and controls was analyzed on the same batch and the
same day after quality control evaluation to prevent any random and systemic error
in reporting value.
Statistical Analysis
The statistical analyses were performed using a Med Cal statistical software and Statistical
Package for Social Sciences for Windows version 17.0 (SPSS Inc, Chicago, Illinois,
United States). Data were expressed as mean ± standard deviation (continuous variables)
or as percentages of total (categorical variables). Two-group comparisons were made
using chi-square for categorical variables and Student's t-tests for continuous variables. Mann–Whitney U test and Kruskal–Wallis test were used to compare the median. The odds ratio (OR)
was calculated by conditional logistic regression to detect the risk of EOC occurrence.
For all analyses, two-sided probability values less than 0.05 were considered statistically
significant.
Results
The mean acceptance rate of the study protocol was 68.25% (n = 200) by eligible participants (n = 293; EOC patients, n = 141; healthy participants, n = 152) and there was no difference between patients versus control group in the number
of participants who refused to participate in the study or withdrew after the initial
consent (p = 0.07; EOC patients, n = 41; healthy controls, n = 52).
[Table 1] depicts the subgroup statistics and analysis of data for clinical characteristics
of the study participants. Healthy controls had an average age of 51.0 ± 10.04 years,
while EOC patients had an average age of 52.8 ± 11.82 years, and there were no significant
difference in age (p = 0.24), age at menarche (p = 0.37), age at full-term pregnancy (p = 0.67), age at menopause (p = 0.31), parity (p = 0.98), phase of menstrual cycle at the time of blood collection (p = 0.92), menopausal status (p = 0.77), duration of menopause (p = 0.96), OCP use (p = 0.28), HRT use (p = 0.86), and smoking (p = 0.82) between ovarian cancer patients and controls. After hospital admission, the
mean duration of EOC confirmation and venous sampling for hormone assay was 12 days ± 4
days and 16 hours ± 6 hours, respectively.
Table 1
Baseline characteristics features of study participants
|
Features
|
Ovarian cancer cases (N = 100)
|
Controls (N = 100)
|
p-Value
|
|
Overall age (mean ± SD, in years)
|
52.8 ± 11.82
|
51.0 ± 10.04
|
0.24[a]
|
|
Age at menarche (mean ± SD, in years)
|
13.5 ± 1.9
|
13.3 ± 1.2
|
0.37[a]
|
|
Age at full term pregnancy (mean ± SD, in years)
|
25.5 ± 5.3
|
25.2 ± 4.9
|
0.67[a]
|
|
Age at menopause (mean ± SD, in years)
|
49.5 ± 4.6
|
48.9 ± 3.7
|
0.31[a]
|
|
Parity, n (%)
|
|
0
|
28 (28.0)
|
27 (27.0)
|
0.98[b]
|
|
1–2
|
44 (44.0)
|
45 (45.0)
|
|
|
> 2
|
28 (28.0)
|
28 (28.0)
|
|
|
Menstrual cycle day, n (%)
|
|
Follicular phase (0–12 d)
|
16 (38.1)
|
15(34.1)
|
0.92[b]
|
|
Ovulation phase (13–16 d)
|
10 (23.8)
|
10 (22.7)
|
|
|
Luteal phase (17–34 d)
|
16 (38.1)
|
19 (43.2)
|
|
|
Menopause status, n (%)
|
|
Premenopausal
|
42(42.0)
|
44 (44.0)
|
0.77[b]
|
|
Postmenopausal
|
58 (58.0)
|
56 (56.0)
|
|
|
Duration of menopause, n (%)
|
|
< 5 y
|
14 (24.1)
|
13 (23.2)
|
0.96[b]
|
|
5–10 y
|
20 (34.5)
|
21 (37.5)
|
|
|
> 10 y
|
24 (41.4)
|
22 (39.3)
|
|
|
OCP use, n (%)
|
|
Yes
|
20 (20.0)
|
28 (28.0)
|
0.28[b]
|
|
Never
|
80 (80.0)
|
72 (72.0)
|
|
|
HRT use, n (%)
|
|
Yes
|
24 (24.0)
|
23 (23.0)
|
0.86[b]
|
|
Never
|
76 (76.0)
|
77 (77.0)
|
|
|
Smoking
|
|
Yes
|
11 (11.0)
|
12 (12.0)
|
0.82[b]
|
|
Never
|
89 (89.0)
|
88 (88.0)
|
|
|
Histopathology, n (%)
|
|
Mucinous
|
44 (44.0)
|
–
|
–
|
|
Serous
|
40 (40.0)
|
–
|
–
|
|
Endometrioid
|
8 (8.0)
|
–
|
–
|
|
Clear cell
|
4 (4.0)
|
–
|
–
|
|
Anaplastic
|
4 (4.0)
|
–
|
–
|
|
Grade
|
|
Well differentiated - Grade 1
|
14 (14)
|
–
|
–
|
|
Moderately differentiated - Grade 2
|
66 (66)
|
–
|
–
|
|
Poorly differentiated - Grade 3
|
20 (20)
|
–
|
–
|
|
FIGO staging
|
|
Early (Stage I and II)
|
24 (24.0)
|
–
|
–
|
|
Advanced (Stage III and IV)
|
76 (76.0)
|
–
|
–
|
Abbreviations: FIGO, International Federation of Gynecology and Obstetrics; HRT, hormone
replacement therapy; OCP, oral contraceptive pill; SD, standard deviation.
a
p-Values are calculated by Student's t-test.
b
p-Values are calculated by Chi-square test.
Among the inducted ovarian cancer cohort, mucinous histopathological type of malignancy
was most common, observed in 44% (n = 44) of patients; 40 patients (40%) had a serous type, tailed by endometrioid (8%),
clear cell (8%), and anaplastic (4%) histopathological type. The majority of the cases
(66%) were moderately differentiated (grade 2), followed (20%) by poorly differentiated
(grade 3) and well-differentiated, grade 1 (14%). In addition, 76 patients (76%) were
in advanced as per the International Federation of Gynecology and Obstetrics (FIGO)
staging, and 24% were in early FIGO staging. All cases and controls were matched according
to infertility, tubal ligation, and hysterectomy (data not shown). Thus, there was
no significant difference in baseline characteristics and clinical variables among
cases and controls, indicating that the EOC and control groups were well matched.
[Table 2] represents group statistics and data analysis for serum levels of FSH, LH, testosterone,
and DHEA-S in ovarian cases and control individuals. The median values of serum LH
were 47.7 and 48.7 IU/L in control and patients, respectively. The corresponding values
for testosterone were 0.39 and 0.42 ng/mL, respectively. Median estimated serum FSH
and serum DHEA-S levels in healthy controls were 45.5 IU/L and 142.2 ug/dL, respectively.
Equivalent values in EOC patients were 58.9 IU/L and 163.43 ug/dL, respectively, that
is, the increase in serum FSH (p = 0.02) and DHEA-S (p = 0.03) levels in patients were statistically significant.
Table 2
Serum level of FSH, LH, testosterone, and DHEA-S in study participants
|
Hormones in median and range
|
Ovarian cancer cases (N = 100)
|
Controls (N = 100)
|
p-Value[a]
|
|
FSH (IU/L)
|
58.9 (8.3–106.7)
|
45.5 (6.6–101.2)
|
0.02
|
|
LH (IU/L)
|
48.7 (4.3- 98.2)
|
47.7 (2.9–81.3)
|
0.67
|
|
Testosterone (ng/mL)
|
0.42 (0.12–0.80)
|
0.39 (0.09–0.78)
|
0.75
|
|
DHEA-S (ug/dL)
|
163.43 (99.4–258.9)
|
142.2 (96.5–245.4)
|
0.03
|
Abbreviations: DHEA-S, dehydroepiandrosterone-sulfate; FSH, follicle-stimulating hormone;
LH, luteinizing hormone.
a
p-Values are calculated by Mann-Whitney U test.
The relationship between FSH tertiles and various variables has been shown in [Table 3] to have a stratified analysis for the association with EOC; serum FSH levels are
expressed as low (< 32.5 IU/L), mid (32.5–72.6 IU/L), and high (> 72.6 IU/L) tertiles.
High tertile FSH level was found to be significantly associated with increased risk
of ovarian cancer compared with low and mid tertile level, in women with parity of
0 to 2 (OR = 2.7, confidence interval [CI] = 1.17–6.30; p trend = 0.03) and in postmenopausal women (OR = 3.0, CI = 1.24–7.29, p trend = 0.04). However, the statistically significant trend observed in postmenopausal
women remained only for the subgroup with menopause duration of greater than 10 years
(OR = 5.9, CI = 1.33–26.66, p trend = 0.04). High tertile FSH level was also found to be significantly allied with
increased risk of ovarian cancer in subgroups who never used to smoke (OR = 3.7, CI = 1.7–8.18,
p trend = 0.02), never used OCP (OR = 2.5, CI = 1.17–5.51, p trend = 0.04), and never used HRT (OR = 3.1, CI = 1.39–7.15, p trend = 0.01).
Table 3
Association of serum FSH level with the occurrence of epithelial ovarian cancer
|
FSH (IU/L)
|
Low tertile
< 32.5
|
Mid tertile
32.5–72.6
|
High tertile
> 72.6
|
p trend
|
|
Parity of 0–2
|
|
Case
|
18
|
22
|
32
|
0.03
|
|
Controls
|
26
|
29
|
17
|
|
OR (95% CI)
|
1.0(ref.)
|
1.1 (0.48–2.48)
|
2.7 (1.17–6.30)
|
|
Menopause status
|
|
Premenopausal
|
|
Case
|
12
|
13
|
17
|
0.20
|
|
Controls
|
19
|
14
|
11
|
|
OR (95% CI)
|
1.0 (ref.)
|
1.4 (0.51–4.18)
|
2.4 (0.85–6.97)
|
|
Postmenopausal
|
|
Case
|
13
|
14
|
31
|
0.04
|
|
Controls
|
24
|
13
|
19
|
|
OR (95% CI)
|
1.0 (ref.)
|
1.9 (0.72–5.47)
|
3.0 (1.24–7.29)
|
|
Duration of menopause
|
|
≤ 10 y
|
|
Case
|
09
|
07
|
18
|
0.44
|
|
Controls
|
13
|
08
|
13
|
|
OR (95% CI)
|
1.0 (ref.)
|
1.2 (0.33–4.74)
|
2.0 (0.65–6.06)
|
|
> 10 y
|
|
Case
|
04
|
07
|
13
|
0.04
|
|
Controls
|
11
|
05
|
06
|
|
OR (95% CI)
|
1.0 (ref.)
|
3.8 (0.76–19.46)
|
5.9 (1.33–26.66)
|
|
Never used OCP
|
|
Case
|
20
|
25
|
35
|
0.03
|
|
Controls
|
32
|
18
|
22
|
|
OR (95% CI)
|
1.0 (ref.)
|
2.2 (0.79–5.06)
|
2.5 (1.17–5.51)
|
|
Never used HRT
|
|
Case
|
17
|
29
|
30
|
0.01
|
|
Controls
|
34
|
24
|
19
|
|
OR (95% CI)
|
1.0 (ref.)
|
2.4 (1.09–5.34)
|
3.1(1.39–7.15)
|
|
Never used to smoke
|
|
Case
|
17
|
33
|
39
|
0.02
|
|
Controls
|
38
|
37
|
23
|
|
OR (95% CI)
|
1.0 (ref.)
|
1.9 (0.95–4.10)
|
3.7 (1.7–8.18)
|
Abbreviations: CI, confidence interval; FSH, follicle-stimulating hormone; HRT, hormone
replacement therapy; OCP, oral contraceptive pill; OR, odds ratio.
Note: OR is calculated by conditional logistic regression.
The relationship between DHEA-S tertiles and various variables has been shown in [Table 4] to have a stratified analysis for the association with EOC, and serum DHEA-S levels
are expressed as low (< 106.9 ug/dL), mid (106.9–194.26 ug/dL), and high tertile (>
194.2 ug/dL). High tertile DHEA-S level was found to be significantly associated with
increased risk of ovarian cancer compared with low and mid tertile level, in women
with parity of 0 to 2 (OR = 2.9, CI = 1.23–7.13; p trend = 0.02) and in premenopausal women (OR = 3.8, CI = 1.26–11.61, p trend = 0.03). High tertile DHEA-S was also found to be significantly associated
with increased risk of ovarian cancer in subgroups who never used to smoke (OR = 2.7,
CI = 1.33–5.67, p trend = 0.01), never used OCP (OR = 3.1, CI = 1.35–7.15, p trend = 0.01), and never used HRT (OR = 2.5, CI = 1.10–5.33, p trend = 0.02).
Table 4
Association of serum DHEA-S level with the occurrence of epithelial ovarian cancer
|
DHEA-S (ug/dL)
|
Low tertile
< 106.9
|
Mid tertile
106.9–194.2
|
High tertile
> 194.2
|
p trend
|
|
Parity of 0–2
|
|
Case
|
13
|
24
|
35
|
0.02
|
|
Controls
|
22
|
30
|
20
|
|
OR (95% CI)
|
1.0 (ref.)
|
1.3 (0.56–3.23)
|
2.9 (1.23–7.13)
|
|
Menopause status
|
|
Premenopausal
|
|
Case
|
7
|
10
|
25
|
0.03
|
|
Controls
|
15
|
15
|
14
|
|
OR (95% CI)
|
1.0 (ref.)
|
1.4 (0.42–4.75)
|
3.8 (1.26–11.61)
|
|
Postmenopausal
|
|
Case
|
17
|
21
|
20
|
0.52
|
|
Controls
|
21
|
18
|
17
|
|
OR (95% CI)
|
1.0 (ref.)
|
1.4 (0.58–3.53)
|
1.4 (0.58–3.60)
|
|
Duration of menopause
|
|
≤ 10 y
|
|
Case
|
10
|
14
|
10
|
0.77
|
|
Controls
|
12
|
11
|
11
|
|
OR (95% CI)
|
1.0 (ref.)
|
1.5 (0.48–4.83)
|
1.1 (0.32–3.61)
|
|
> 10 y
|
|
Case
|
07
|
07
|
10
|
0.55
|
|
Controls
|
09
|
07
|
06
|
|
OR (95% CI)
|
1.0 (ref.)
|
1.2 (0.30–4.42)
|
2.1 (0.52–8.81)
|
|
Never used OCP
|
|
Case
|
19
|
26
|
35
|
0.01
|
|
Controls
|
27
|
29
|
16
|
|
OR (95% CI)
|
1.0 (ref.)
|
1.2 (0.57–2.80)
|
3.1 (1.35–7.15)
|
|
Never used HRT
|
|
Case
|
19
|
28
|
29
|
0.02
|
|
Controls
|
35
|
20
|
22
|
|
OR (95% CI)
|
1.0 (ref.)
|
2.5 (1.15–5.74)
|
2.5 (1.10–5.33)
|
|
Never used to smoke
|
|
Case
|
23
|
29
|
37
|
0.01
|
|
Controls
|
41
|
23
|
24
|
|
OR (95% CI)
|
1.0 (ref.)
|
2.2 (1.06–4.75)
|
2.7 (1.33–5.67)
|
Abbreviations: CI, confidence interval; DHEA-S, dehydroepiandrosterone-sulfate; HRT,
hormone replacement therapy; OCP, oral contraceptive pill; OR, odds ratio.
Note: OR is calculated by conditional logistic regression.
[Table 5] represents the association of serum FSH and DHEA-S level with clinicopathological
features of ovarian cancer. There was no significant association of serum FSH level
with either histopathological type (p = 0.29), or grading (p = 0.23), or staging (p = 0.13) of ovarian cancer. While serum DHEA-S was found to be statically significant
allied with well-differentiated (p = 0.02) ovarian tumor compared with moderately and poorly differentiated grade, and
early FIGO staging (p = 0.001) compared with late FIGO staging of EOC. Median values of DHEA-S in early
FIGO staging (stage I and II) were 154.7 ug/dL (range = 99.4–258.9 ug/dL), while comparative
value in late FIGO staging was 120.5 ug/dL (range = 85.4–199.7 ug/dL) of EOC.
Table 5
Association of serum FSH and DHEA-S level with clinicopathological features
|
Serum FSH (IU/L)
|
Serum DHEA-S (ug/dL)
|
|
Histopathology
|
|
Serous type
|
48.9 (16.3–98.7)
|
153.9 (96.7–258.9)
|
|
Nonserous type
|
51.2 (8.3–106.7)
|
150.7 (99.4–237.8)
|
|
p-Value[a]
|
0.29
|
0.21
|
|
Grade
|
|
Well differentiated
|
48.2 (16.3–92.2)
|
164.8 (85.4–258.9)
|
|
Moderately differentiated
|
52.3 (25.4–106.7)
|
149.8 (95.8–210.9)
|
|
Poorly differentiated
|
50.1 (8.3–92.5)
|
136.5 (99.4–196.7)
|
|
p-Value[b]
|
0.23
|
0.02
|
|
Staging
|
|
Early staging (I and II)
|
51.2 (18.3–92.7)
|
154.7 (99.4–258.9)
|
|
Late staging (III and IV)
|
54.3 (30.4–106.7)
|
120.5 (85.4–199.7)
|
|
p-Value[b]
|
0.13
|
0.001
|
Abbreviations: DHEA-S, dehydroepiandrosterone-sulfate; FSH, follicle-stimulating hormone.
a
p-Values are calculated by Mann–Whitney U test.
b
p-Values are calculated by Kruskal–Wallis test.
Discussion
Incessant ovulation and gonadotropin hypothesis are the two foremost elucidations
for EOC etiology; however, limited experimental and epidemiologic evidence supports
either of these. Moreover, research on prediagnosis endogenous androgens/gonadotropins
concentration and EOC risk is scarce and has yielded inconclusive results. Therefore,
this study considered it worthwhile to assess the prediagnostic serum levels of testosterone,
DHEA-S, FSH, and LH with the EOC risk. We undeniably found a significant positive
association of FSH and DHEA-S with the increased risk. These findings are in accord
with some studies,[22]
[23]
[24]
[25] but in contrast to others.[26]
[27]
In the primary analysis, prediagnostic levels of FSH (p = 0.02; [Table 2]) and DHEA-S (p = 0.03; [Table 2]) were elevated in EOC patients compared with healthy controls. Moreover, it was
found that both elevated FSH and DHEA-S were associated with augmented risk for the
occurrence of EOC after adjusting for various confounding factors and effective modifiers.
However, this study failed to find any association of circulating blood level of LH
and testosterone with the occurrence of EOC, while that was not the case in Ose et
al[27] and Keri et al[28] but in agreement with Halperin et al[29] and Tworoger et al.[30]
Among the study participants, the median level of FSH was 29.45% higher (p = 0.02) in cases (58.9 IU/L) than controls (45.5 IU/L). The same is substantiated
by a study[22] reporting an increased gonadotropin level in the fluid of ovarian cancer, which
might have originated from the high circulating level of gonadotropin. The association
between serum FSH level expressed as tertiles and the risk of EOC reveals that high
tertile level was significantly associated with increased risk of EOC in various subgroups,
namely parity of 0 to 2, menopausal duration greater than 10 years, smoking habit,
and participants who never used OCP or HRT. The adjusted OR comparing the highest
third tertile with the bottom third quartile was 2.7 (95% CI = 1.17–6.3; p = 0.03) for subgroup defined as parity of 0 to 2; 5.9 (95% CI = 1.33–26.66; p = 0.04) for menopausal duration greater than 10 years; 2.5 (95% CI= 1.17–5.51; p = 0.03) for subgroup who never used OCP; 3.1 (95% CI = 1.39–7.15; p = 0.01) for subgroup who were never on HRT; and 3.7 (95% CI: 1.7–8.18; p: 0.02) for subgroup who never used to smoke. This is in stark contrast to Arslan
et al[26] and McSorley et al,[31] wherein a high level of FSH have been reported to be a protective factor for ovarian
cancer, but in concordance with the great majority of the researches[22]
[32]
[33]
[34] and also in line with the gonadotropin hypothesis of ovarian carcinogenesis.
The pathophysiology behind the observed effect seems to be follicular development,
resultant in the effect of FSH on theca and granulose cells.[23] High gonadotropin entraps the ovarian epithelial cells in an inclusion cyst, and
causes augmented estrogenic stimulation of ovarian epithelial cells, which is responsible
for its increased proliferation and subsequent malignant transformation. Excess gonadotropins
are prime to the development of ovarian cancer as they have also been associated with
surge during ovulation and deficient gonad negative feedback for premature ovarian
failure and menopause. There is a suggestive inverse association between pregnancy
and OCP with ovarian cancer risk by decreasing gonadotropins via steroidal feedback
on the pituitary gland[23]
[24]; similar relationships persisted in the current study ([Table 3]), further providing epidemiologic evidence in support of the gonadotropin hypothesis.
With repute to circulating LH, we have not found any evidence of an association between
serum LH level and EOC, and neither we observed any protective effect of LH on ovarian
cancer, as exemplified by Helzlsouer et al.[35] This is in harmony with Halperin et al[29] and Akhmedkhanov et al.[36] However, a handful of observations are also in conflict with the gonadotropin hypothesis,
as illustrated by Ushiroyama et al[37] that estrogen replacement therapy, which reduces circulating gonadotropins and,
thus, should confer protection, appears to be associated with a moderately increased
risk of ovarian cancer.[38]
We did not observe any statistically significant association with testosterone and
risk of EOC in premenopausal or postmenopausal women or overall, similar to that of
Rinaldi et al[9] and Lukanova et al.[25] Among the study participants, the median level of DHEA-S was 14.92% higher (p = 0.03) among cases (163.43 ug/dL) than among controls (142.2 ug/dL). The association
between serum DHEA-S levels expressed as tertiles and the risk of EOC reveals that
a high tertile level of DHEA-S was significantly associated with increased risk of
EOC in premenopausal women. Compared with women categorized in the lowest third of
DHEA-S concentrations in the premenopause subgroup, the OR increased to 1.4 (95% CI = 0.42–4.75)
and 3.8 (95% CI = 1.26–11.61) in the middle and highest thirds, respectively. Comparable
results were obtained through conditional logistic regression analysis in other subclassified
groups (namely parity of 0–2, never used to smoke, and participants who never used
OCP and HRT), also there was a progressive increase in OR from the middle to highest
third tertile group of DHEA-S compared with the lowest third ([Table 4]). Our observed associations also seem consistent with Helzlsouer et al.[35]
DHEA-S is a major circulatory androgen in women derived from the adrenal glands. Animal
model studies have provided strong evidence that ovarian cancer preferentially progresses
in a hormonal milieu enriched with androgens by accelerating proliferation of epithelial
cells of the ovary directly through androgen receptor signaling[6] and reduced apoptotic rates or through their role as estrogen precursors.[39] Androgens have also been associated with the increased invasive potential of ovarian
epithelial cells by stimulating matrix metalloproteinases.[40] Taken together, androgens (directly or after conversion to estrogens) may contribute
to growth promotion and/or differentiation in the early stages of the disease. On
evaluating the association between studied parameters and clinicopathological features
of the disease (histopathological type, grading, and staging), it was found that DHEA-S
level was significantly high in well-differentiated tumor and early stage of ovarian
cancer; this pattern exhibited by DHEA-S with ovarian cancer risk is unique and is
challenging to explain the underlying pathophysiology. While serum FSH did not unveil
any association with either histopathological type (p = 0.29), or grading (p = 0.23), or staging (p = 0.13) of ovarian malignancy.
To the best of our knowledge, based on the PubMed database, this is the first study
in the North Indian population to detect the role of gonadotropins and androgens in
the development of ovarian cancer. Other potential strengths of the study include
the selection criteria of the patient cohort as patients with features suggestive
of any other malignancy or benign ovarian tumors were excluded, thus confined the
study to EOC; we designed and performed this study in a manner where we adjusted several
confounding variables and effective modifiers, thus rule out or at least minimizes
the possibility of any biases that may lead to potential false-positive or false-negative
results. Finally, prediagnostic samples were used for the biochemical variable analysis,
thus minimizing the possibility of the disease's effect on the circulating hormones.
Nonetheless, our findings described here are only statistical observations, provide
only the association's evidence, and cannot provide a causal relationship. Other limitations
include that this study was performed in a relatively small population from one hospital,
which may not represent the entire patient population. The generalizability of these
findings will need to be confirmed in future multicentric prospective design studies
after incorporating larger groups with the inclusion of other hormones like estrogen,
progesterone, and sex hormone binding globulin. Despite these limitations, we believe
that the findings of this study can be helpful for outcome predictions, and variables
pointed here should be added to the screening profile of EOC. However, alliance or
enmity in some subgroups/variables warrants additional evaluation.
Conclusion
To summarize and conclude, our study reveals a statistically significant elevated
prediagnostic circulating concentration of serum FSH and DHEA-S in EOC patients compared
with healthy controls. Furthermore, these abnormalities were significantly associated
with increased occurrence of EOC, in particular, elevated FSH in postmenopausal and
DHEA-S in premenopausal women. Thus, this study, in unification with prevailing prospective
epidemiological studies, supports the hypothesis that circulating FSH and DHEA-S concentrations
is a putative risk factor for ovarian cancer. This emphasizes the need to add these
variables in the screening profile of EOC for early recognition and scheduling necessary
interventions/management strategies.
