Breast cancer incidence rates are increasing worldwide. In India, it is the most common cancer among women in many regions and has overtaken cervix cancer, which was the commonest cancer a decade ago. The continuing rise in breast cancer incidence has created an urgent need to develop strategies for prevention. Breast cancer appears to have a complex etiology, possibly with interplay of many causal factors including hormonal, genetic and environmental factors operating over a long period. Although several risk factors have been well defined, the interactions of the various etiological factors are yet to be completely understood. Moreover, analysis of newer parameters like family history could be helpful in screening high risk women for developing breast cancer, followed by planning of future, preventive and treatment modalities.
Age of the cancer patient is an important factor both for occurrence and management of the case. Average age of the patients seen in the six hospital based cancer registries in the National Cancer Registry Project (NCRP) network for the period 1994–98 was found to range from 44.2 years in Dibrugarh to 49.6 years in Bangalore and Chennai registries. In the present study the average age of the breast cancer case at presentation was found to be 47.9 years. Our findings are in agreement with the findings of the NCRP network . Similarly, the average age of breast cancer patients has been reported to be 50 to 53 years in various population-based registries located in different parts of the country . Similar hospital based studies carried-out at Delhi and Jaipur have also reported that the average age of breast cancer cases to be as 46.8 and 47 years [24, 25]. The average age of occurrence of breast cancer amongst US white females has been reported to be 61.0 years . The average age of occurrence of the breast cancer in India reveals that the disease occurs a decade earlier, as compared to western countries. The reason for early age of occurrence amongst Indian females needs to be further studied. A similar viewpoint has been put forward by a study conducted by Borovanova  in the Czech population. In their study, they found a shift of cancer more towards younger women.
Epidemiological studies carried out in the country have shown variation in the incidence of breast cancer among different religious groups such as Hindus, Muslims, Christians, Parsi and Buddhists. Breast cancer incidence by religion for greater Bombay population indicated highest incidence rates among Parsis and Christians and lowest rates among Jains and Buddhists. In another study from Chennai, the rates have been shown to be highest among Christians followed by Hindus and Muslims. Similarly in Trivandrum study, the incidence rates have been reported to be highest among Christians followed by Hindus and Muslims. Paymaster et al , in an analysis of hospital cancer cases by major religious groups have shown the variation in relative frequency between religious groups and in particular, high percentage among Parsi women compared to other religious communities. The reason for high incidence of breast cancer in Parsi community is as a result of their more westernized life-style, conserved genetic pool, high frequency of consanguineous marriages and higher age at the time of marriage and child birth . In our study, on comparison of relative frequencies of cancer cases by various religious groups with that of population distribution of Delhi by these religious groups revealed that Christians had a higher percentage of cancer. Although Christians accounted for only 0.88% in the general population but relative frequency of cancer cases in the present study were 5.8%. The other two religions had more or less similar proportions. Although, the age at presentation amongst Christian patients was highest (51.5 years), as compared to other two religions, no significant difference was noticed in stage at presentation and lymph node status. The possible explanation for high incidence and higher age at presentation amongst Christians may be the same as in Western population.
Few studies of international variation in breast cancer have considered tumor histology. The histological type of carcinoma whether it is invasive or an in situ type are features which carry an inbuilt understanding of their general behavior pattern. In a study conducted by Wynder et al , comedo carcinoma and medullary carcinoma were found to be more frequent in Tokyo. Cases from a broader range of hospitals in Boston and Tokyo revealed occurrence of tumors of better prognostic types viz. intraductal, medullary and colloid types in Tokyo than in Boston. It is important to understand the relationship of histological type to etiology, and to allow separation of entities with distinct etiologies.
Histology as a prognostic factor has been well documented. Patients with histology of Infiltrating duct carcinoma (IDC)(NOS) have a poor survival compared to other types . In the present study among the different histomorphological types, Infiltrating duct Carcinoma (NOS) was found to be the most common type i.e. in 502 cases (86.9%). The histological distribution of female breast cancers seen during the years 1984–93 in the hospital based cancer registries under the network of NCRP revealed that, in Mumbai, Bangalore and Thiruvananthapuram 83.3%, 85.0%, and 83.3% cases had a histology of infiltrating duct carcinoma while, 2.7%, 1.7%, 1.6%, belonged to lobular carcinoma, and the remaining 14.0%, 13.3%, 15.2% cases respectively were of other histopathological subtypes . Infiltrating duct carcinoma was the commonest type seen in our series. The findings of the present study are almost in agreement with the findings reported by the hospital based cancer registries under the NCRP network. In the US population also, infiltrating ductal type of breast carcinoma was found to be the commonest histological type . Among the age-correlation with various histomorphological types, prognostically better tumours like juvenile secretory were more commonly observed amongst younger females while infiltrating ductal carcinoma and lobular carcinoma remained the two most common cancers amongst elderly patients. It was also noted that ILC was present in a higher proportion in familial group (12.5%) as compared to non-familial cases (5.4%) in the present study, however it was not found statistically significant.
It is well known that breast cancer cases diagnosed at an earlier stage have a more favorable prognosis compared to those detected at late stage. However, because lack of awareness, fear of disease and psychological reasons, most of the patients in our country try to ignore or hide the disease and by the time they come to the hospital, the disease is already in the late stages. In the present study, over 90% of cases are in stages II, III and IV. The findings of the present study reveal that breast cancer frequently presents at higher stage i.e. 36.1% cases presenting with Stage IIIB in Indian population. This reflects a need for awareness and to initiate programs for early diagnosis of the cancer.
Numerous studies carried out in India and western populations have identified various reproductive factors generally associated with breast cancer [9–11, 13, 29–31]. A case-control study to identify risk factors for breast cancer carried out in Mumbai, India indicated that single women compared to married women had 4–5 fold higher risk for development of breast cancer in the age group of 40–54 years and 55 and above . In another study it has been shown that nulliparous women had 2.2-fold higher risk than parous women . High incidence of breast cancer among Parsi women was partly due to more unmarried women, late age at marriage and first child, less children and consanguinity of marriage . Nulliparity and late age at first birth are the consistently observed reproductive risk factors . In our study only 6 cases (1.0%) were found to be unmarried and four married woman (0.6%) were nulliparous.
Family history is another risk-factor for breast carcinoma. It has been noted that women who have first degree relative with breast cancer have a risk two to three times that of general population, the risk further increased if the relative was affected at an early age and/or had bilateral disease . There is a greater risk if more than one close relative is affected, if breast cancer has occurred at a young age in a family member or if a patient has bilateral disease . One of the explanations for familial aspects of breast cancer is germline mutation in BRCA1, BRCA2, p53 and other genes . These cellular genes, which comprise dominantly acting oncogenes and recessively acting tumour suppressor genes, have been shown to contribute to genetic predisposition to variety of human cancers. In the present study, 20.2% cases revealed a positive family history of cancer. Out of these, higher percentages of cases 29.0% were observed in females under 44 years of age as compared to 15% in women of above 45 years of age. The presence of family history doubled the risk of subsequent breast cancer among younger women. In a similar study by Marcus et al, the relative risk of breast cancer was found to be doubled by the presence of a family history of breast cancer and amplified by younger age. It has been stated that there might be considerable underestimation of hereditary breast cancers. The studies carried-out at Jaipur and Delhi have reported the family history of cancer as 10% and 8% in their series. With documentation of pedigree, familial breast cancer (FBCs) may constitute as high as one third of the total incidence of breast cancers and approximately one forth of them would fall into the subset of hereditary breast cancer (HBC). It has been observed that familial breast cancer patients have an improved rate of survival, thereby indicating importance of noting familial cancer cases . The present study clearly implies the importance of taking an appropriate history for eliciting family histories from the relatives. It is crucial to elicit detailed personal and family history extending back to atleast three generations, checking the medical records including pathology reports, wherever possible it is better to complete an accurate pedigree and taking family history from both maternal and paternal side of family. History of cancers among family members helps in identifying high risk groups, who can be counselled and subjected to careful follow ups with early diagnostic modalities and can even choose certain therapies. Improved ways of follow up with study of various interacting genes would also be useful to identify high-risk groups. Therefore, it is imperative to include parameters like family history for better understanding of breast cancer causation and predisposition.
Breast cancer usually presents with a single hard lump as is evident in the present study with occurrence of bilaterality in only 5 out of total 569 cases. In an earlier study, bilaterality was reported in 3% of breast cancer patients . FBC have been observed to be having improved survival, as a result of stringent monitoring which may help in diagnosis at early stage [30, 35]. Clinical stage is another factor implicated. In a study conducted by Langlands et al , FBC cases had a lower stage of presentation. However, in our study, no such association was observed.