Relationship between diverting stoma and adjuvant chemotherapy in patients with rectal cancer: a nationwide study using the National Database of Health Insurance Claims and Specific Health Checkups of Japan.

Patients at risk of recurrence after curative surgery for rectal cancer usually receive adjuvant chemotherapy. Postoperative recovery after low anterior resection (LAR) for rectal cancer can be improved by placement of a diverting stoma to reduce anastomotic leakage. However, it remains unclear how a diverting stoma affects administration of adjuvant chemotherapy in these patients. We identified Japanese patients with rectal cancer who underwent LAR in 2014 and received adjuvant chemotherapy within 12 months of surgery in the National Database of Health Insurance Claims and Specific Health Checkups of Japan. Doses of five types of chemotherapy administered (tegafur/uracil, tegafur/gimeracil/oteracil potassium, capecitabine, 5-fluorouracil, and oxaliplatin) were assessed according to the presence or absence of diverting stoma and the timing of stoma closure. There was no significant difference in the cumulative doses of chemotherapy administered in the 12 months after LAR between patients with and without diverting stoma, but more doses were administered in the early postoperative period (0–2 months after LAR) in patients without diverting stoma. Also, more doses of chemotherapy, regardless of type, were administered in the late closure group (7–12 months after LAR) than in the early closure (≤ 6 months) and no closure groups. Presence of a diverting stoma did not influence the dose of adjuvant chemotherapy administered within 12 months after LAR but could have delayed the start of adjuvant chemotherapy. Patients with late closure of a diverting stoma received more doses of adjuvant chemotherapy administered over 12 months.