The Validity of a New Edition of Classification for Ovarian Metastasis from Colorectal Cancer

Objectives In the 9th edition of the Japanese Classification of Colorectal, Appendiceal, and Anal Carcinoma (JCCRC), ovarian metastasis is classified as distant metastasis. We assessed the significance of resection of ovarian metastases and the validity of this 9th edition of JCCRC for ovarian metastases from colorectal cancer (CRC). Methods We retrospectively analyzed the clinicopathological factors and overall survival of 17 patients with ovarian metastases from CRC who underwent resection and 110 female CRC patients with Stage IV (M1a) disease. Results The patients with only ovarian metastases who underwent resection had a longer median survival time than patients with both ovarian and peritoneal metastases who underwent resection (45.4 months vs. 9.3 months, P = 0.029). The 5-year overall survival of the patients with only ovarian metastases who underwent R0 resection was as long as that of the female Stage IV (M1a) CRC patients after R0 resection (50% vs. 48%, P = 0.334). Conclusions We found that, after resection, patients with only ovarian metastases had significantly better prognoses than patients with ovarian and peritoneal metastases. R0 resection of ovarian metastasis indicated as good prognosis as R0 resection of metastasis to one distant organ without ovaries. So the 9th edition of JCCRC, which classifies ovarian metastasis from CRC as distant metastasis, is appropriate.