CRC accounts for approximately 15% of all deaths in patients with IBD [6, 7]. The risk of CRC for patients with IBD increases by 0.5% to 1% yearly from 8 to 10 years after the IBD diagnosis. A meta-analysis of published studies that focused on the CRC risk in UC showed that the risk of CRC for patients with colitis was 2% at 10 years, 8% at 20 years, and 18% after 30 years of colitis . Previously, CD was not considered a risk factor for CRC; however, recent studies have shown that the CRC risk in patients with colonic CD is similar to that of patients with UC [7, 9].
In patients with IBD, CRC can take the form of sporadic cancer or colitis-associated cancer. In patients with UC who develop colitis-associated cancer, total proctocolectomy is the standard treatment; however, when sporadic cancer occurs, total proctocolectomy is not always necessary. In patients with CD, an indication for total proctocolectomy has been controversial. However, it was also reported that, when a diagnosis of colitis-associated cancer is known in advance of surgery, a total proctocolectomy should be seriously considered, to eliminate the risk of metachronous disease. In 44% of these patients, dysplasia occurred at a site remote from the site of the cancer . However, this patient had already undergone ileocecal resection and the residual small intestine was 230 cm long, resulting in intestinal failure syndrome requiring home parental nutrition. For these reasons, we chose abdominoperineal resection with colostomy, not total proctocolectomy with ileostomy, in order to preserve the colon and maintain absorption of water and electrolytes. After the last surgery, we conducted intensive cancer surveillance and neither a recurrence nor another lesion has been detected at this time.
However, the site of inflammation should be resected, owing to the risk of dysplasia. When the colon and rectum are preserved in surgery, a scheduled, annual surveillance with biopsies is strongly recommended . It is very important, when planning therapy and surveillance after surgery, to perform a differential diagnosis to distinguish between colitis-associated CRC and sporadic CRC. However, it is often difficult to achieve this differential diagnosis in patients with IBD, particularly before surgery [11, 12].
The American Gastroenterological Association and the British Society for Gastroenterology surveillance guidelines have recommended beginning surveillance after 8 to 10 years of disease in cases of CD or extensive UC, and after 15 to 20 years of disease in cases of left-sided UC [13–15]. However, the evidence on which this is based on is poor. It was reported that cancer has occurred in a substantial number of patients with IBD (17% to 28%) before the recommended time intervals for surveillance .
Clinically, endoscopic examination is the most useful screening method. However, even with endoscopic examination, it is often difficult to detect dysplastic changes. Colitis-associated dysplasia may show subtle macroscopic features that mimic a broad variety of lesions, ranging from inflammation to carcinoma. Previous reports have indicated that dysplastic lesions were not visible upon endoscopy in 50% to 80% of cases with colitis-associated cancers . Conversely, sporadic cancer mainly develops from polyps that are on the pathway to becoming adenoma-carcinomas, and a polyp is easily detectable, even in a normal endoscopy examination. In contrast, the gross appearance of colitis-associated neoplasms varies from case to case, as the neoplasm develops from dysplasia to become a carcinoma. Dysplastic lesions may be irregularly delineated, plaque-like, irregularly elevated, or verrucous structures; therefore, they are difficult to identify with normal endoscopy .
This case should make surgeons and endoscopists aware of the possibility that patients with CD may develop either colitis-associated cancer or sporadic cancer. This report should alert surgeons and endoscopists to look for colitis-associated cancers that are in a precancerous or early stage. In this case study, although we performed annual colonoscopic surveillance, we did not detect the second lesion, the colitis-associated cancer, until it reached an advanced cancerous stage. Early detection is highly important for avoiding surgeries, including colectomy or proctectomy. However, it is often difficult to detect colitis-associated cancers in dysplastic, precancerous, or early stages. We need further investigation to discover novel biomarkers that make it possible to detect cancer in blood samples or biopsies.