The negative impact of understaging rectal cancer patients

Neo-adjuvant chemoradiation followed by surgery and adjuvant therapy is standard treatment of clinical node positive rectal cancer. Understaging leads to delay in treatment with possible detrimental results. This study analyses effects of understaging stage III rectal cancer on long-term outcomes. A consecutive series of patients, operated on in MGH between 2004 and 2015 was included. Outcomes of non-neoadjuvantly treated clinical stage I patients who turned out to have pathological stage III disease and neoadjuvantly treated clinical stage III patients were retrospectively reviewed. The latter group was subdivided into patients who had persistent nodal disease (ypN+) and patients without positive lymph nodes after neoadjuvant treatment (ypN0). Of the 204 included patients, 30 had unexpected nodal disease on pathology. Clinical stage I-patients had higher rates of local recurrence, and rectal cancer and overall mortality than ypN0-patients. Understaging stage III rectal cancer led to poorer oncologic outcomes, when compared to patients without positive lymph nodes on pathology after neoadjuvant. Future research should focus on identifying patients with treatment susceptible lymph node involvement. •Understaging stage III rectal cancer led to higher rates of local recurrence.•Understaging stage III rectal cancer lead to higher rates mortality.•Identifiers for patients who will be treatment susceptible are needed.