Vasectomy and prostate cancer: a case-control study in India.

BACKGROUND: The role of vasectomy in the development of prostate cancer remains controversial. In particular, there has been concern about detection bias and confounding in the previously published epidemiological studies examining this hypothesis. With the goal of minimizing detection bias, we have evaluated the relation between vasectomy and prostate cancer in a population without routine prostate cancer screening. METHODS: A case-control study consisting of 175 prostate cancer cases and 978 controls with cancer diagnoses other than prostate cancer was conducted at hospitals covered by the Bombay Cancer Registry in Bombay, India. History of vasectomy, demographic, and lifestyle factors were obtained by structured interview. Multiple logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI). RESULTS: Standardizing by age, 8.7% of cases and 8.3% of controls had had a vasectomy. The OR for prostate cancer comparing men who had had a vasectomy to those who did not was 1.48 (95% CI: 0.80-2.72) controlling for age at diagnosis, smoking status, alcohol drinking, and other demographic and lifestyle factors. Risk of prostate cancer associated with vasectomy appeared to be higher among men who underwent vasectomy at least two decades prior to cancer diagnosis or who were at least 40 years old at vasectomy. CONCLUSIONS: Although not statistically significant, the results of this hospital-based case-control study are consistent with the hypothesis of a positive association between vasectomy and prostate cancer. Because routine prostate cancer screening is not common in this population, detection bias was unlikely to account for this association.

PIP: Although several studies have detected an association between vasectomy and subsequent prostate cancer, the research has been marred by detection bias and confounding. This association was reassessed in a hospital-based case-control study conducted in India, where the absence of routine screening for prostate cancer eliminates the potential for detection bias. Enrolled from hospitals covered by the Bombay Cancer Registry were 175 prostate cancer cases and 978 controls with other types of cancers. 17 cases and 83 controls reported a history of vasectomy. After age was controlled, the odds ratio for prostate cancer was 1.31 (95% confidence interval (CI), 0.74-2.33) among vasectomized compared with nonvasectomized men. Further adjustment for confounding factors such as smoking, alcohol consumption, and marital status increased the relative risk to 1.48 (95% CI, 0.80-2.72). Compared with men without a vasectomy history, men who underwent the procedure more than 20 years earlier had 1.56 times the risk (95% CI, 0.79-3.08) of prostate cancer. Men who were 40 years of age or older at vasectomy had a relative risk of prostate cancer of 2.10 (95% CI, 1.02-4.31) compared with controls; this risk was not elevated in younger men. Overall, these findings confirm the hypothesis of a small but positive association between prostate cancer and vasectomy.

Oesophageal cancer in India.

Oesophageal cancer has a high incidence rate in India and both males and females are affected almost equally. A study of high-risk factors associated with this disease is presented. Bidi smoking, pan chewing with or without tobacco, and alcohol drinking are the factors strongly associated with oesophageal cancer in Bombay.

Descriptive epidemiology of lymphatic malignancies in Greater Bombay.

Lymphoid malignancies as a group constitute one of the important cancers met in India as elsewhere in the world, but while information on incidence, mortality, survival and trends, are available from most of the developed countries, there are very few reports available from the rest of the world. The basic data utilized for this study was obtained from the Bombay Cancer Registry, the first population based registry to be established in India. Descriptive epidemiology of these malignancies was obtained by utilizing 5-year data of incidence and mortality of different cell types in males and females. For studying time trends in the incidence of these cancers, data of the past 30 years has been used. As a group, the lymphatic malignancies represent only 5% of the incidence and 3.9% of the mortality of the total number of cancers in Greater Bombay. Males in general, seem to be more affected by lymphomas than females. Non-Hodgkin's lymphomas are the commonest lymphatic malignancies to be detected in Bombay. The incidence curves show striking difference in lymphatic malignancies by cell type. In Bombay the incidence of these cancers was found to be the highest in the Parsis. Our data indicates that there is an increasing trend in incidence in all cell types of lymphomas, in both sexes. To obtain the details of the risk factors of these malignancies, more analytic epidemiological studies have to be undertaken of the Indian data and more importance given to lymphomas in the early detection and control of cancer.

Descriptive epidemiological assessment of urinary bladder & kidney cancers in Greater Bombay.

For studying the descriptive epidemiology of cancers of the urinary bladder and kidney, the data reported by Bombay Cancer Registry for the most recent five years have been utilised. For studying time trends in these cancers, data of the past 30 yr have been used. In Bombay, bladder cancer is very uncommon in the first three decades of life; but after the age of 30, the incidence rates increase with age, in log-linear fashion, in both sexes. The incidence of kidney cancer is almost absent between the ages 5 to 35; but later up to the age of 70, it show a steady increase. The incidence of urinary bladder and kidney cancers are found to be associated with the marital status in both sexes. No association was observed between the incidence and educational level attained by the patients having urinary bladder and kidney cancers. An increasing trend was found in the age adjusted incidence rates of cancers of the urinary bladder and kidney in both sexes during the period 1964-1993.

Descriptive epidemiology of leukaemias in Greater Mumbai.

BACKGROUND: There is little data available on the occurrence of leukaemias in India. This is despite a large number of patients being diagnosed and treated at various cancer centres all over the country. We, therefore, analysed the available data of the Bombay Cancer Registry to ascertain the epidemiological characteristics of leukaemias in India. METHODS: The incidence and mortality rates of leukaemias by cell type and sex were obtained for the most recent 5 years (1989-93). The data of the past 30 years were used to study the time trends using a linear regression model based on the logarithms of the incidence rates. RESULTS: Leukaemias constituted 3.9% of all registered cancer cases and 5.4% of all registered deaths in Greater Mumbai. Males were affected more frequently than females. Myeloid leukaemias were the commonest. A bimodal age incidence was observed with the first peak in childhood, a trough between 15 to 19 years of age and a slow rise thereafter. Among the various religious groups Hindus had the highest rate. An increasing trend in the incidence of all types of leukaemias was also observed. CONCLUSION: The incidence of leukaemias in Greater Mumbai is comparable to world rates. There is a male preponderance in all cell types and an increase in incidence was observed over the last 30 years. The higher incidence of myeloid leukaemias observed by us might be related to under-reporting of chronic lymphatic leukaemia.

Descriptive epidemiology of the cancers of male genital organs in greater Bombay.

For different reasons cancers of the Prostate, Testis and Penis are important diseases for men. The incidence for prostate and testicular cancers are more commonly seen in developed countries, while penile cancer occurs more frequently in the developing countries. In Mumbai the incidence of prostatic and testicular cancers is low whereas penile cancer is high when compared with international reports. In Mumbai. The incidence of prostatic cancer increases only after the age of 50. The age specific incidence rates for testicular cancers are bimodal whereas the incidence of Penile cancer increases exponentially with age, after the age 30. In Mumbai. The incidence of Prostate cancer was six times higher in the Parsis as compared to other communities. The incidence of cancer of the testis is lowest in Hindus and cancer of penis is not seen in Muslims. The incidence of prostate cancer was highest among Gujrathis and there was an absence of penile cancer in Urdu speaking men. In Bombay the incidence of cancers of the prostate, testis and penis seem to be associated with marital status. The association between incidence and education level of the patients was only found in men having cancer of the testis. There seems to be an increase in age adjusted incidence rates for cancers of the prostate and testis over time period of 30 years, whereas penile cancer incidence was decreasing over the same period.

Descriptive epidemiology of bone cancer in greater Bombay.

Bone tumours are comparatively uncommon, constituting only 0.5% of the total world cancer incidence. As Bone tumors consist of several distinct clinico-pathological entities, descriptive epidemiology of tumors at this site can be based only on studies where they can be distinguished. Ewing's sarcoma Chondrosarcoma and Osteosarcoma are the principal tumors involving bones. The basic data utilized for this study was collected from the Bombay Cancer Registry which was established in 1963, and is the first population based registry to be established in India. For studying the descriptive epidemiological variables the most recent 5 year incidence rates have been used. As a group, bone cancers represent 0.9% of the total number of incident cancer are seen in Greater Bombay. Males in general are seen to have a higher incidence of bone cancers than females. Ewing's sarcoma was found to be the commonest bone cancer in Bombay. The age specific incidence curves present striking differences according to cell types of bone cancer. Time trends in the incidence of these cancers, over the past 30 years have been presented. Our data indicate that there is a decreasing trend in incidence of bone cancers in females, whilst the rates are stable in males. Ionising radiation is the only environmental agent to cause this cancer. The discovery of other risk factors is the key prevention and will depend upon the experimental work undertaken to develop sub-clinical measures of risk that can be applied in interdisciplinary studies to identify more completely the causes of bone cancers.

Geographic differences in cancer incidence by sex at various sites in city wards in Greater Bombay.

In this paper an attempt has been made to study the geographic variations in cancer incidence at various sites, by sex, in Greater Bombay. Crude incidence rates at each site for individual wards have been calculated using the data collected by the Bombay Cancer Registry, for the years 1979 to 1984. To study the variations highest and lowest crude incidence rates in the different wards and the ratio of the highest to the lowest rates for each primary site were calculated. Detailed analyses show that there is a positive relationship between male and female rates for certain sites such as the Buccal Mucosa, Oesophagus, Stomach, Colon, Rectum and Liver. The Tongue, Oropharynx, Hypopharynx, Lung and Larynx present rates that vary widely in males but only slightly in females. Sites such as the Pancreas, Hodgkin's Disease, Lymphoma and Leukaemias do not seem to present any particular pattern. It was interesting to find that those sites where environmental factors are of likely value, such as excessive tobacco chewing and smoking tend to fall in the second category. Particularly striking is the the fact, that habits of etiological value are those to which men are more frequently addicted to than women, probably explaining the low rates in females of the wide variation in male rates.

The descriptive epidemiology and trends in incidence of nonocular malignant melanoma in Bombay and India.

Nonocular malignant melanoma is a rare but lethal disease increasing in incidence and mortality in western countries with improved survival if diagnosed and treated early. This study reports its epidemiology from cancer registry data in six different parts of India; its anatomic distribution and trends in Bombay from 1964 to 1984. Age-adjusted incidence in Bombay patients shows no increase from 1964 to 1984 unlike in white caucasians. Males exceed females in patients 45 years or older unlike whites, but are equalled or exceeded by females in those less than 45 years. The sole of foot and internal mucous membranes are its major anatomic sites in Indians as in negroid blacks. This cancer in Indians resembles that in blacks and nonwhites in affecting less pigmented epithelia and skin. Susceptible melanosomes and ultraviolet light exposure may both be involved in its aetiopathogenesis.