Benefit of adjuvant systemic chemotherapy in signet ring colorectal cancer: A systematic review

Abstract Background Signet ring colorectal cancer (SRC) is a rare histological subtype associated with young patients and worse outcomes. Its incidence is anticipated to increase with the rising rate of early‐onset colorectal cancer. There is little literature on the benefit of adjuvant systemic therapy in this patient cohort. Methods A systematic review of the literature was undertaken to evaluate the response of SRC to adjuvant systemic therapy. The study was pre‐registered in the PROSPERO database. The MEDLINE/PubMed, EMBASE, Scopus, Web of Science and CENTRAL databases were searched for pertinent articles. Articles published from inception to June 2025 were retrieved and assessed by two independent reviewers. Results Of the initial 31 studies retrieved, four were deemed eligible for inclusion, with a total number of 6900 patients. All were population‐based retrospective cohort studies. All studies demonstrated a statistically significant survival benefit for adjuvant therapy in non‐metastatic SRC. Conclusions Adjuvant systemic therapy has a beneficial impact on survival in Stage III SRC, and should be utilised in patients with adequate performance status. The benefit in Stage II remains unclear.