Prostate Cancer - An Epidemiological Study in India

Abstract

Tutkimuksen tavoitteena oli löytää eturauhasen syövän syytekijöitä kehitysmaan pienen vaaran väestössä. Erityisesti tutkittiin vasektomian, siviilisäädyn, ravinnon, tupakoinnin ja alkoholin vaikutusta. Aineisto kerättiin Mumbaissa Intiassa tapaus-verrokkitutkimuksena. Alkuperäiset tapaukset olivat Bombayn väestöpohjaiseen syöpärekisteriin ilmoitetut 594 eturauhasen syöpätapausta vuosilta 1998 2000. Kaksi verrokkia valittiin potilaan asuinalueelta. Verrokit ja elossa olevat potilaat tai kuolleen potilaan omaiset haastateltiin. Lopulliseen aineistoon hyväksyttiin 390 potilasta ja 780 verrokkia. Tutkittavien tekijöitten vaikutusta mitattiin vetosuhteina.

Eturauhasen syöpävaara vasektomiaryhmässä oli 2-4 kertaa suurempi kuin ei-vasektomoiduilla. Suurentuneen vaaran uskottavuutta heikensivät huomattavasti valikoituneisuuteen ja haastattelun luotettavuuteen liittyvät tekijät. Miehillä, jotka olivat menneet yli 25 vuotiaina naimisiin oli myös suurentunut eturauhasen syöpävaara nuorempana naimisiin menneisiin verrattuna. Miehillä, jotka ilmoittivat syövänsä paljon hedelmiä ja vihanneksia, oli pieni eturauhasen syöpävaara. Muilla ravintotekijöillä, juomilla tai tupakoinnilla ei ollut vaikutusta eturauhasen syöpävaaraan.

Vasektomian haitallisilla terveysvaikutuksilla olisi huomattavia seurauksia kehitysmaitten syntyvyyden säännöstelyyn ja väestöpolitiikkaan. Vasektomiaa koskevat tulokset tuleekin varmentaa hyvin suunnitelluilla epidemiologisilla tutkimuksilla Intiassa ja muissa kehitysmaissa.

Objective: The objectives of this study were to find out the etiological factors for prostate cancer from a low risk population of a developing country. The specific aims were to assess the role of the following risk/protective factors: vasectomy, marital history, dietary habits, tobacco habits, and alcohol habits.

Methods: Keeping the objectives of this study as the guidelines, a questionnaire was prepared for data collection. The questionnaire consisted of the following sections, 1. Identification particulars 2. Socio-demographic parameters 3. History of vasectomy 4. General dietary patterns 5. Tobacco and alcohol habits

Included in this study were microscopically proved cases of prostate cancer diagnosed during 1998 to 2000 and registered by Bombay Population Based Cancer Registry (n=594). The controls were healthy men belonging to the resident general population of Mumbai, India. Two controls for each case matched by age and place of residence were selected as the comparison group. The exposure history of the cases and controls were collected by structured face to face interviews. After exclusions, 390 cases and 780 controls were available for final analysis. The adjusted odds ratios were estimated by multiple logistic regression method. Results: Vasectomy has been emerged as a risk factor for prostate cancer. Compared with no vasectomy the OR for ever having undergone vasectomy was 1.9 after controlling for age and other possible confounding factors. The risk for those who had a vasectomy before the age of 45 years was 2.1 fold and those who had it at a later age (45 years or later) was 1.8 fold compared to those who did not had a vasectomy. Also those who had completed more than 2 decades after had a vasectomy showed a 3.8 fold risk for prostate cancer compared to those who did not had a vasectomy.

Late marriage, that is, men who married at the age of 25 years or later, was associated with a 2.5 fold risk for prostate cancer compared with those who married at younger ages, before the age of 25 years.

The role of certain dietary factors including fruits and vegetables, fish, meat, coffee, tea and oil/fat intake on prostate cancer indicated that those who consumed more than 2 kilograms of fruits and vegetables in a week showed a protective effect for prostate cancer compared to those who consumed less than 2 kilograms of fruits and vegetables and the dose response was statistically significant, intake of fish, meat showed no statistically significant association with prostate cancer, consumption of non-alcoholic beverages like coffee, tea were not significantly associated with prostate cancer but high quantities of oil/fat consumption (more than 2 kilograms of oil/fat per month) showed an insignificant increased risk for prostate cancer. Tobacco smoking or tobacco chewing were not significantly associated with prostate cancer. Also there were no dose response relationships for number of bidi, cigarette smoked or time since start of these habits. Alcohol drinking (wine, whisky or toddy) did not show any statistically significant association with prostate cancer neither any dose response was observed for number of times drank or time since start of these habits.

Conclusion: There are major public health and birth control implications on vasectomy increases the risk for prostate cancer. It is likely, however, that biases identified in this study result in high estimates of risk and the true risk due to vasectomy is substantially less than the estimated one. Due to the several limitations and possibilities for biases in this study, the evidence for the estimates obtained may not be a strong one. However, these results may give clues for further investigations and so prospective studies with good design and conduct are required for a better understanding of the etiology of prostate carcinogenesis