Journal of Cancer Research and Therapeutics

: 2006  |  Volume : 2  |  Issue : 3  |  Page : 97--99

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

Madhumay Pal 
 Department of Radiotherapy, Institute of Postgraduate Medical Education and Research and S.S.K.M. Hospital, Kolkata, India

Correspondence Address:
Madhumay Pal
21/1A, R. K. Ghosal Road, Kolkata - 700 042


Aim: Colorectal cancer is particularly a disease affecting individuals above 40 years of age and 90% of cases occur in persons over the age of 50. Genetic and familial factors, viz, HNPCC and FAP, contribute to less than 20% and environmental or acquired factors are the cause of the rest. The aim of this study is to find out the relative proportion of patients <40 years of age affected by this disease, registered in our institute. Materials and Methods: Colorectal cancers registered in the calendar years of 2003 and 2004 in our institute were analyzed in this study. Data from Population Based Cancer Registry (P.B.C.R.) for Bangalore, Mumbai, Delhi and Chennai for the year 1988 were taken for comparison. Results: The results show that our institute«SQ»s figures exceed the generally accepted figure for «SQ»incidence of the disease below the age of 40 years«SQ» by less than 10% of both the total incidence of the disease and those of P.B.C.R. for Bangalore, Mumbai and Chennai. The corresponding figure for females in Delhi P.B.C.R. shows a little similarity to our institute«SQ»s figure. Conclusion: This observation indicates a changing pattern of colorectal cancer occurrence. This change may be a regional one or may be a result of genetic or environmental changes.

How to cite this article:
Pal M. Proportionate increase in incidence of colorectal cancer at an age below 40 years: An observation.J Can Res Ther 2006;2:97-99

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Pal M. Proportionate increase in incidence of colorectal cancer at an age below 40 years: An observation. J Can Res Ther [serial online] 2006 [cited 2021 Apr 14 ];2:97-99
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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.


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].


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.


Now, further study is required to be undertaken to find out whether this is due to regional factors or whether it is indicative of a changing pattern of occurrence of colorectal cancers. If the second reason prevails, it is to be found out whether it is due to genetic factors or factors related to environmental changes, including changing food habits.


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


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