Study of intra-abdominal fat distribution in sigmoid colon cancer in Japanese patients by use of MDCT data.

To assess the relationship between intra-abdominal fat and sigmoid colon cancer, we investigated the intra-abdominal fat distribution in 172 examples of sigmoid colon cancer and 767 examples of various other pathologies by using data from multidetector-row computed tomography. One significant finding was that the intra-abdominal fat area in sigmoid colon cancer presents a small secondary peak in the pelvis on the profile of the intra-abdominal fat, which we called the pelvic sub-peak. The presence or absence of the pelvic sub-peak was determined based on the sub-peak ratio, which was calculated by dividing the maximum peak by the sub-peak value on the profile of the intra-abdominal fat area. The pelvic sub-peak was defined as having a sub-peak ratio >or=0.1. The pelvic sub-peak frequency was higher for all male patients than for female patients. The frequency of the pelvic sub-peak in sigmoid colon cancer was 77.5% (79/102) for men and 50.0% (35/70) for women. Among both men and women, frequencies of the pelvic sub-peak were significantly higher in patients with sigmoid colon cancer than in non-tumor cases (P < 0.001). Furthermore, the frequency of the pelvic sub-peak was almost the same in sigmoid colon cancer as in rectal cancer. No causal relationship between sigmoid colon cancer and a pelvic sub-peak could be confirmed in the present study; however, patients with sigmoid colon cancer tended to exhibit a unique pattern of fat accumulation.