Abstract
Axillary lymph node status remains an important prognostic factor in early breast
cancer. It is regarded as an indicator for (neo)adjuvant systemic treatment and postoperative
radiotherapy of the regional lymphatics. Commenced in September 2015, the INSEMA trial
is investigating whether operative determination of nodal status as part of breast
conserving therapy (BCT) for early stage breast cancer (c/iT1–2 c/iN0) can be avoided
without reducing oncological safety. After inclusion of 1001 patients there was general
acceptance of the complex study design by patients and study doctors so that recruitment
for the first randomisation (axillary sentinel lymph node biopsy [SLNB]: yes or no)
achieved predicted case numbers. The second randomisation however (SLNB alone versus
complete axillary dissection when one or two macrometastases are present at SLNB)
recruited fewer cases than expected for the following three reasons: a) the 13 % rate
of one or two macrometastases after SLNB in the INSEMA trial collective was lower
than expected; b) around 20 % of patients refused the second randomisation; c) there
was delayed inclusion of the Austrian study centres, which only recruited for the
second randomisation. Lack of knowledge of nodal status when SLNB is avoided represents
a new challenge for the postoperative tumour board. In particular decisions on chemotherapy
for luminal-like tumours and irradiation of the lymphatics (excluding axilla) must
be guided by tumour biological parameters. The INSEMA trial does not provide answers
to some important questions, e.g. it remains unclear whether patients without SLNB
can be offered partial breast irradiation alone in low-risk situations and whether
SLNB can also be avoided in patients with stage T1–2 tumours who have a mastectomy
indication.
Key words breast cancer - INSEMA trial - nodal status - sentinel lymph node biopsy - radiotherapy