Who can benefit from a lymph node boost in definitive chemoradiotherapy for node-positive cervical cancer: an evaluation of nodal failure in patients without nodal boost

This study was performed to identify risk factors for pelvic nodal failure (PNF) after definitive concurrent chemo-radiotherapy (CCRT) in patients with metastatic pelvic lymph nodes (mPLNs) from squamous cell carcinoma (SCC) of the cervix. We retrospectively reviewed data on 80 patients who received definitive CCRT between 2005 and 2014 at our hospital. All patients underwent brachytherapy and whole-pelvic radiotherapy (WPRT) without nodal boost. mPLNs was diagnosed by magnetic resonance imaging and positron emission tomography. The rate of PNF and factors affecting PNF were analysed. A total of 156 mPLNs were found. The median number of mPLNs was 2 per patient (range 1–6); the median short diameter was 1.7 cm (range 1.0–4.2 cm). After a median follow-up of 64 months, 10 (6.4%) mPLNs failed in 13 (16.3%) patients. The 5-year PNF-free survival (PNFFS), disease-free survival and overall survival rates were 83.4, 62.7 and 74.7%, respectively. The mPLN size was not associated with the risk of PNF. However, pre-radiotherapy SCC antigen (SCC-Ag) >6.8 ng/mL and number of mPLNs >2 were significant risk factors for PNF. Using the two risk factors, we categorized the patients into three risk groups. The 5-year PNFFS rates in patients with 0, 1 and 2 risk factors were 100.0, 78.3 and 44.4%, respectively (P < 0.01). SCC-Ag level and number of mPLNs were significant factors for PNF. Patients with both risk factors developed frequent PNF after WPRT without nodal boost. The two risk factors can be a guide in deciding whether to administer nodal boost radiotherapy.