Rare tumors of the colon and rectum: a national review.

BACKGROUND: Most literature available on rare colorectal cancer (CRC) is from case series reports. This population-based evaluation is the first comprehensive look at four rare histologic types of CRC, allowing comparisons with the more common adenocarcinoma for clinical and pathological features and survival rates. MATERIALS AND METHODS: All patients diagnosed with carcinoid (n=2,565), malignant lymphoma (n=955), non-carcinoid neuroendocrine (n=455), squamous cell (n=437), and adenocarcinoma (n=164,638) in SEER cancer database (1991-2000) were analyzed. Evaluation of age-adjusted incidence rate, stage at presentation, and 5-year relative survival were determined for each histologic subtype. RESULTS: All rare histologic subtypes had younger mean age than adenocarcinomas (70 years; p<0.05). Lymphoma was more common in males (65.1%; P<0.01). Incidence rates in 2000 per million were: carcinoid 10.6, lymphoma 3.5, neuroendocrine 2.0, squamous 1.9, and adenocarcinoma 496.3. The annual percent change in incidence for each rare tumor increased significantly during the 10 years (range: 3.1-9.4%, p<0.05), except squamous cell carcinoma (5.9%, p>0.05). Squamous (93.4%) and carcinoid (73.7%) tumors occurred more often in the rectum; lymphoma (79.0%), neuroendocrine (70.8%), and adenocarcinoma (70.1%) occurred more often in the colon (P<0.01). Carcinoids presented at earlier stage (localized/regional, 90.5%) more often than adenocarcinoma (80.6%; p<0.01), but squamous cell (82.1%; p=0.50), lymphoma(70.6%; p<0.01), and neuroendocrine (37.8%; p<0.01) presented at earlier stage similarly or less often than adenocarcinoma. Relative 5-year survival rate was highest for carcinoid (91.3%), and lowest for neuroendocrine tumors (21.4%). CONCLUSION: This study provides the first population-based analysis of the epidemiology, tumor characteristics, and survival rates for rare CRC.

Malignancies of the appendix: beyond case series reports.

PURPOSE: A comprehensive analysis was performed for five histologic types of appendiceal tumors to compare incidence, clinicopathologic features, survival, and appropriateness of surgery. METHODS: All patients diagnosed with mucinous adenocarcinoma (n = 951), adenocarcinoma (n = 646), carcinoid (n = 435), goblet (n = 369), and signet-ring cell (n = 113) in the Surveillance, Epidemiology, and End Results database (1973-2001) were analyzed. Evaluation of incidence, stage, and five-year relative survival were determined for each histology. The appropriateness of the operative procedure (i.e. , appendectomy vs. colectomy) was examined by tumor type and size. RESULTS: Tumor incidence, patient demographics, survival outcomes, and appropriateness of surgery varied significantly among the different appendiceal tumor histologies. The most common appendiceal tumors were mucinous. With regard to patient demographics, carcinoids presented at an earlier mean age of 41 years and 71 percent were female (P < 0.001 for both). Overall five-year survival was highest for carcinoid (83 percent) and lowest for signet ring (18 percent). Although current guidelines specify that a right hemicolectomy (rather than an appendectomy) be performed for all noncarcinoid tumors and carcinoid tumors >2 cm, we found that 30 percent of noncarcinoids underwent appendectomy. Similarly, 28 percent of carcinoids >2 cm under-went appendectomy, which is a lesser resection than is indicated. CONCLUSIONS: This study provides a population-based analysis of epidemiology, tumor characteristics, survival, and quality of care for appendiceal carcinomas. This characterization provides a novel description of the presentation and outcomes for malignancies of the appendix and highlights that a substantial number of patients with appendiceal tumors may not be receiving appropriate surgical resection.

A 10-year outcomes evaluation of mucinous and signet-ring cell carcinoma of the colon and rectum.

PURPOSE: Most studies examining mucinous or signet-ring cell colorectal cancers are single institution reports. This study used a national cancer registry to analyze the epidemiology and survival outcomes of these two subtypes of colorectal cancer compared with adenocarcinoma tumors. METHODS: All patients diagnosed with mucinous (n = 16,991), signet-ring cell (n = 1,522), or adenocarcinoma (n = 146,115) colorectal cancer in the Surveillance, Epidemiology, and End Results database (1991-2000) were evaluated. Analyses were performed to obtain age-adjusted incidence rates, stage at presentation, tumor grade, and five-year relative survival for each subtype. RESULTS: Mucinous were slightly more common in females (53.4 percent). Incidence rates per 100,000 persons were: mucinous, 5.5; signet-ring cell, 0.6; and adenocarcinoma 46.6. The annual percent change during ten years was stable for mucinous, increased for signet-ring cell (4.8 percent; P < 0.05), and decreased for adenocarcinoma (-1.1 percent; P < 0.05). Fewer mucinous (18 percent) and signet-ring cell (21 percent) tumors were located in the rectum compared with adenocarcinoma (29 percent). Signet-ring cell presented at later stage (III/IV, 80.9 percent) more often than mucinous (52.8 percent) and adenocarcinoma (49.5 percent), and also had worse tumor grade (high grade: signet-ring cell, 73.5 percent; mucinous, 20.9 percent; adenocarcinoma, 17.5 percent). Relative five-year survival was worse for signet-ring cell than mucinous or adenocarcinoma. CONCLUSIONS: We present a large population-based review of colorectal cancer subtypes by analyzing national data from the past decade. Although the incidence of colorectal adenocarcinoma is decreasing in the United States, mucinous and signet-ring cell subtypes are stable and increasing, respectively. Importantly, it seems that the signet-ring cell subtype has worse outcomes, whereas survival rates for mucinous tumors are similar to adenocarcinomas.