LAUSR

OBJECTIVE To investigate whether tumor deposits (TDs) in rectal cancer are associated with increased recurrence risk and decreased survival. SUMMARY BACKGROUND DATA Tumor deposits (TDs) are considered a risk factor for recurrence after colon cancer resection and presence of TDs prompts adjuvant chemotherapy. The prognostic relevance of TDs in rectal cancer requires further exploration. METHODS All patients treated with abdominal resection surgery for rectal cancer in Sweden between 2011 and 2014 were eligible for inclusion in this retrospective cohort-study based on prospectively collected data from the Swedish ColoRectal Cancer Registry. Primary endpoint was local recurrence or distant metastasis. Secondary outcomes were overall and relative survival. RESULTS 5455 patients were identified. 3769 patients were analysed after exclusion. TDs were found in 404 (10.7%) patients including where 140 (3.7%) patients with had N1c-status. In TD-positive patients, local recurrence and distant metastasis rates at 5 years were 6.3% [95% CI 3.8-8.8%] and 38.9% [95% CI, 33.6-43.5%] compared to 2.7% [95% CI, 2.1-3.3%] and 14.3% [95% CI, 13.1-15.5%] in TD-negative patients. In multivariable regression analysis, risk of local recurrence and distant metastasis were increased; HR 1.86 [95% CI, 1.09-3.19; P=0.024] and 1.87 [95% CI, 1.52-2.31; P=<0.001] respectively. Overall survival at 5 years was 68.8% [95% CI, 64.4-73.4%] in TD-positive patients and 80.7% [95% CI, 79.4-82.1%] in TD-negative patients. pN1c-patients had similar outcomes regarding local recurrence, distant metastasis and survival as pN1a-b stage patients. TD-positive pN1a-b patients had significantly worse outcomes while TDs did not affect outcomes in pN2a-b patients. CONCLUSION This study suggests that TDs have a negative impact on prognosis in rectal cancer. Thus, efforts should be made to diagnose TD-positive rectal cancer patients preoperatively.