The negative impact of understaging rectal cancer patients

Concordance of MRI With Pathology for Primary Staging of Rectal Cancer in Routine Clinical Practice: A Single Institution Experience

PURPOSE

MRI is the preferred imaging modality for primary staging of rectal cancer, used to guide treatment. Patients identified with clinical stage I disease receive upfront surgical resection; those with clinical stage II or greater undergo upfront neoadjuvant therapy. Although clinical under-/over-staging may have consequences for patients and presents opportunities for organ preservation, the correlation between clinical and pathologic staging in routine clinical practice within a single institute has not been fully established.

METHODS

This retrospective, Institutional Review Board-approved study, conducted at a National Cancer Institute-Designated Comprehensive Cancer Center with a multi-disciplinary rectal cancer disease center, included patients undergoing rectal MRI for primary staging January 1, 2018-August 30, 2020. Data collection included patient demographics, initial clinical stage via MRI report, pathologic diagnosis, pathologic stage, and treatment. The primary outcome was concordance of overall clinical and pathologic staging. Secondary outcomes included reasons for mismatched staging.

RESULTS

A total 105 rectal adenocarcinoma patients (64 males, mean age 57 ± 12.7 years) had staging MRI followed by surgical resection. A total of 28 patients (27%) had mismatched under-/over- staging. Ten patients (10%) were understaged with mismatched T stage group (clinical stage I, pathologic stage II), five (5%) were understaged with mismatched N stage group (clinical stage I, pathologic stage III), and 13 (12%) were overstaged (clinical stage II-III, pathologic stage 0-I). Treatment matched concordance between clinical and pathologic stages was 86%.

CONCLUSION

MRI for primary rectal cancer staging has high concordance with pathology. Future studies to assess strategies for reducing clinically relevant understaging would be beneficial.

Nonoperative Rectal Cancer Management With Short-Course Radiation Followed by Chemotherapy: A Nonrandomized Control Trial

PURPOSE

Short-course radiation therapy (SCRT) and nonoperative management are emerging paradigms for rectal cancer treatment. This clinical trial is the first to evaluate SCRT followed by chemotherapy as a nonoperative treatment modality.

METHODS

Patients with nonmetastatic rectal adenocarcinoma were treated on the single-arm, Nonoperative Radiation Management of Adenocarcinoma of the Lower Rectum study of SCRT followed by chemotherapy. Patients received 25 Gy in 5 fractions to the pelvis followed by FOLFOX ×8 or CAPOX ×5 cycles. Patients with clinical complete response (cCR) underwent nonoperative surveillance. The primary end point was cCR at 1 year. Secondary end points included safety profile and anorectal function.

RESULTS

From June 2016 to March 2019, 19 patients were treated (21% stage I, 32% stage II, and 47% stage III disease). At a median follow-up of 27.7 months for living patients, the 1-year cCR rate was 68%. Eighteen of 19 patients are alive without evidence of disease. Patients with cCR versus without had improved 2-year disease-free survival (93% vs 67%; P = .006), distant metastasis-free survival (100% vs 67%; P = .03), and overall survival (100% vs 67%; P = .03). Involved versus uninvolved circumferential resection margin on magnetic resonance imaging was associated with less initial cCR (40% vs 93%; P = .04). Anorectal function by Functional Assessment of Cancer Therapy-Colorectal cancer score at 1 year was not different than baseline. There were no severe late effects.

CONCLUSIONS

Treatment with SCRT and chemotherapy resulted in high cCR rate, intact anorectal function, and no severe late effects. NCT02641691.