Journal of Cancer Research and Therapeutics Medknow Publications on behalf of the Association of Radiation Oncologists of India (AROI) ISSN: 0973-1482 EISSN: 1998-4138 Vol. 2, Num. 3, 2006, pp. 97-99

Journal of Cancer Research and Therapeutics, Vol. 2, No. 3, July-September, 2006, pp. 97-99

Original Article

Proportionate increase in incidence of colorectal cancer at an age below 40 years: An observation

Pal Madhumay

Department of Radiotherapy, Institute of Postgraduate Medical Education and Research and S.S.K.M. Hospital, Kolkata
Correspondence Address:21/1A, R. K. Ghosal Road, Kolkata - 700 042 Email: madhumay@hotmail.com

Code Number: cr06024

Abstract

Keywords: Colorectal cancer, environmental factors, genetic factors

Introduction

Colorectal cancer is generally a disease affecting individuals 50 years of age or older.[1] The age-specific incidence of colorectal cancer in the United States appears to rise steadily from the second to ninth decade of a person's life. Men have proportionately higher incidence of rectal cancer than women, but both sexes are represented almost equally.[2]
Colorectal cancer develops by a multistep process that can be influenced by hereditary or genetic and environmental or acquired factors. The best documented inherited predispositions to colorectal cancers are hereditary nonpolyposis colorectal cancer (HNPCC) and familial adenomatous polyposis (FAP). HNPCC is associated with abnormalities of many genes involved in DNA repair, whereas FAP is associated with germline mutations of the adenomatous polyposis coli gene. Most cases of colorectal cancers, however, do not have a well documented inherited component; these are referred to as sporadic cases. Such cases result from at least seven somatic mutations and take decades to evolve.[3]

The environmental factors responsible for development of sporadic colorectal cancers are i) age beyond 40 to 45 years[4]; ii) high saturated fat consumption[5]; iii) exposure to ionizing radiation, particularly to pelvic region[6]; iv) overcooked and high red meat consumption[5]; and v) insufficient dietary calcium.[4] In general, the majority of colorectal cancers are likely to occur after 40 years of age. But in recent years, there is an observation of increased incidence of colorectal cancers in younger age group at our institute. In this study, our departmental data are analyzed to testify to this observation.

Materials and methods

Cases of colorectal cancer registered in our institute in the years 2003 and 2004 were studied [Table - 1]. Only carcinomas were included in the study. The aim of this study was to estimate i) the proportion of colorectal cancers in relation to total registered cancer patients, ii) the sex trend for rectal and colon cancers and iii) proportion of rectal and colon cancers occurring below and at or above 40 years of age for both males and females.

As both urban and rural populations of West Bengal are attended to in this government institute, the data from this institute may be taken as representative of this part of the country. Classified data of cancer patients of previous years of this institute not having in hand colorectal cancers registered in Population Based Cancer Registries (P.B.C.R.)[7] for Bangalore, Mumbai, Delhi and Chennai in 1988 [Table - 2] were analyzed on the same lines to estimate any deviation in any parameter if at all.

Results

Rectal cancers in both males and females outnumber colon cancers in our institute [Table - 3]. P.B.C.R. under scrutiny reflects proportionately more rectal than colon cancers in males, but for females this is not always true [Table - 4].

Age-wise, incidence of rectal cancers in males and females below the age of 40 years in our institute are proportionately well above the P.B.C.R. data cited here, excepting female rectal cancers (at < 40 years of age) in Delhi P.B.C.R [Table - 5][Table - 6].

Similarly, incidence of colon cancers in males and females below the age of 40 years reported here are proportionately higher than P.B.C.R. data quoted here, excepting, again, Delhi P.B.C.R. data for females [Table - 5][Table - 6].

Discussion

Colorectal cancer incidence rises sharply after age 45 and 90% of cases occur in persons over the age of 50.[8] Genetic and familial etiologies account for less than 20% of colorectal cancers in the U.S. The remaining 80% of cases are random, with dietary factors affecting risk significantly.[9]

The concern for colorectal cancer affecting young population < 40 years old is due to the poor prognosis attached to it. Dukes and Bussey suggested a much higher rate of lymphatic metastasis in patients less than 40 years of age due to more rapid progression of the disease in young patients. Recio and Bussey reported that 53% of tumors in young patients were of high grade; in comparison, only 20% of tumors were of high grade in the older age group, who are more prone to colorectal carcinoma.[10]

It is apparent from the present study that incidence of colorectal cancer at an age < 40 years in our institute is proportionately higher (more than 20%) for both sexes than the reported data.[8] The figures also exceed the corresponding figures in Bangalore, Mumbai and Chennai P. B. C. R. for 1988. The Delhi P.B.C.R. shows corresponding figures for females comparable to our institute's figures.

Conclusion

Acknowledgment

The author acknowledges the services of Mr. Sisir Kumar Upadhya, Scientific Assistant of this department, who maintains patients' data.

References

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