Rectal cancer, incidence

Although often treated similarly to colon cancer, there are some important differences in the treatment of rectal cancer compared with colon cancer, especially in the adjuvant setting and the role of radiation. Rectal cancer involves tumors found in distal 15 cm of the large bowel and, as such, is very distinct from colon cancer in that it may recur both locally and dis-tally. The higher incidence of local failure and poorer overall... 

Michels KB, Giovannucci E, Joshipura KJ, Rosner BA, Stampfer MJ, Fuchs CS, Codlitz GA, Speizer FE and Willett W. 2000. Prospective study of and incidence of colon and rectal cancers. J Natl Cancer Inst... 

Isacson et al. (1985) examined the association between cancer incidence and indices of water contamination in an ecological study conducted in the central United States. Cancer incidence rates in towns with populations between 1000 and 10 000 were compared by level of volatile organic compounds and metals in the drmking-water. Among men, significant associations between the level of 1,2-dichloroethane (>0.1 ppm) and colon p = 0.009) and rectal cancer p = 0.02) were observed. The authors stated that 1,2-dichloroethane might be an indicator for other types of contamination rather than a causal agent. 

The incidence of colon cancer is greatest among males, who have an age-adjusted incidence rate of 44.3 per 100,000, as compared to females for whom the rate is 34.8 per 100,000. Cancer of the rectum occurs less frequently the incidence rate is 19.1 and 11.6 per 100,000 for males and females, respectively. Cancer of the colon and rectum is the third most frequent malignancy among U.S. men and white and African-American women, but is second next to breast cancer for Hispanic, American Indian/Alaskan Native, and Asian/Paciflc Islander women. The overall incidence of colon and rectal cancers in... 

Michels, K.B., Edward, G., Joshipura, K.J., Rosner, B.A. et al.. Prospective study offruit and vegetable consumption and incidence of colon and rectal cancers, J. Natl Cancer Inst, 92, 1740-1752,2000 [erratum], J. Natl Cancer Inst, 93 (11), 879,2001. 

The colon is a muscular organ and the last part of the digestive system in human, and the rectum is the final portion of the colon. Colorectal cancer is the third most common type worldwide (Boyle and Ferlay, 2005 Parkin, 2004) after limg and stomach cancer. Among them colon cancer is more frequent than rectal cancer. Especially in developed countries, the ratio of colon to rectum cancer cases can increase up to 2 1 or more. However, in nonindustrialized countries, rates are almost similar. On the other hand, comparison of the incidence rate of colon cancer in developed and underdeveloped countries shows that colorectal cancer is more common in industrialized countries. Also 50% of the colorectal cancer death has been seen in developed countries (Tyczynski et al., 2003). It remains relatively uncommon in Africa and much of Asia. And rates of this cancer increase with industrialization and urbanization. It has been much more common in high income countries, but also now increasing in middle- and low-income countries too. It remains relatively higher in North America, Europe, and Australia rather than South America, Asia, and Africa (Parkin, 2004). 

Sheldon PW et al. (1974) The incidence of lung metastases in C3H mice after treatment of implanted solid tumors with X-rays or surgery. Br J Cancer 30(4) 342 348 SRC Trial Group (1997) Improved survival with preoperative radiotherapy in resectable rectal cancer. Swedish Rectal Cancer Trial. N Engl J Med 336(14) 980-987 Stausbol-Gron B, Overgaard J (1999) Relationship between tumor cell in vitro radiosensitivity and clinical outcome after curative radiotherapy for sqiuimous cell carcinoma of the head and neck. Radiother Oncol 50(l) 47-55 Stuschke M, Thames HD (1999) Fractionation sensitivities and dose-control relations of head and neck carcinomas analysis of the randomized hyperfractionation trials. Radiother Oncol 51(2) 113-121... 

A case-cohort study conducted in Denmark similarly examined plasma ENL and colorectal cancer and found significantly lower incidence rate ratios (IRR) for colon cancer among women for each doubling of plasma ENL concentration (IRR 0.76 95% Cl 0.60—0.96). Interestingly, however, rectal cancer in men was associated with an increased risk for every doubling of plasma ENL concentration (IRR 1.74 95% Q 1.25—2.44). ... 

Retrospective mortality studies99 in 2,567 workers (> 3 months employment) from two capacitor manufacturing plants showed that mortality in both plants was lover than expected and there were no significant increases in either liver or rectal cancer. A study on 31 workers exposed to Aroclor 1254 and other chemicals vtiile employed in a New Jersey petrochemical plant 100 showed an increased incidence of malignant melanomas (0.04% expected 0.13% observed) however, due to the small populations involved in this survey, more comprehensive long term epidemiologic studies will be required to fully assess the carcinogenicity of PCBs. Hovever, it is apparent from most reports that occupational exposure to PCBs results in characteristic toxic symptoms vhich appear to be reversible. 

The data on anticancer effects of DR on humans are limited. It has been shown in humans that obese persons subjected to DR have decreased rectal cell proliferation, a biomarker related to colon cancer. In a recent retrospective study in Swedish women, it was noted that women with less caloric intake had substantially lower incidence of breast cancer. These reports indicate that the anticancer effects of DR observed in the experimental models are reproducible in humans. 

The cancers that exhibited a significant inverse relationship between green tea consumption and disease incidence are colon, rectal, pancreatic, stomach, ovarian, and gastrointestinal tract cancers. In most of the cases, the epidemiological data were... 

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