A cohort study of untreated metastatic breast cancer revealed that adjuvant regional nodal irradiation (RNI) reduces distant recurrences to a greater extent than regional recurrences, despite only targeting the regional lymph nodes, according to a study published in JAMA Network Open.
The analysis included 597 women with positron emission tomography and computed tomography (PET-CT) images that could be adequately analysed to ascertain the extent of regional nodal involvement at metastatic diagnosis using standard nodal assessment criteria. The primary outcome was the likelihood of regional nodal involvement at the time of metastatic breast cancer presentation and was determined by reviewing pre-treatment PET-CT imaging and lymph node biopsy findings.
Regional lymph node involvement was exhibited by 512 (85.8%) of women with metastatic breast cancer. Lymph node involvement was more prevalent among oestrogen receptor-negative tumours (92.4%) than oestrogen receptor-positive tumours (83.6%). Nodal involvement at the time of metastatic diagnosis was not associated with overall survival.
These findings suggest that most patients with untreated breast cancer who present with distant metastases also exhibit concurrent regional lymph node involvement, supporting the hypothesis that regional nodal disease may precede and contribute to the seeding of distant foci, the authors conclude.