Epidemiology of cancer of the cervix: global and national perspective

Cancer of the uterine cervix is one of the leading causes of cancer death among women worldwide. The estimated new cancer cervix cases per year is 500,000 of which 79% occur in the developing countries. Cancer cervix occupies either the top rank or second among cancers in women in the developing countries, whereas in the affluent countries cancer cervix does not even find a place in the top 5 leading cancers in women. The truncated rate (TR) in the age group 35-64 years in Chennai, India, is even higher (99.1/100,000; 1982-95) than rate reported from Cali, Colombia (77.4/100,000, 1987-91). The cervical cancer burden in India alone is estimated as 100,000 in 2001 AD. The differential pattern of cervical cancer and the wide variation in incidence are possibly related to environmental differences. Aetiologic association and possible risk factors for cervical carcinoma have been extensively studied. The factors are: Sexual and reproductive factors, socio-economic factors (education and income), viruses e.g., herpes simplex virus (HSV), human papillomavirus (HPV), human immunodeficiency virus (HIV) in cervical carcinogenesis and other factors like smoking, diet, oral contraceptives, hormones, etc. The accumulated evidence suggests that cervical cancer is preventable and is highly suitable for primary prevention. Sexual hygiene, use of barrier contraceptives and ritual circumcision can undoubtedly reduce cervical cancer incidence. Education, cervical cancer screening of high risk groups and improvement in socio-economic status can reduce cervical cancer morbidity and mortality significantly.

Survival from contralateral breast cancer

First primary, or unilateral, breast cancer (UBC) cases diagnosed in 1960-89 at the Cancer Institute (WIA), Chennai, India were followed-up until December 31, 1994. Patients with UBC (n = 3163) and those who developed second cancer in the contralateral breast (CBC) after the initial breast cancer (n = 67 or 2.1% of UBC) were analysed. Compared to UBC patients, those who developed CBC were younger at the time of diagnosis of initial breast cancer and had higher frequency of breast cancer among the family members. The relative survival rate takes into account competing causes of death and was estimated as the ratio of observed survival rate to the expected survival rate. The cumulative relative survival from UBC at 5 and 10 years were 51% and 41%, respectively, and the corresponding rates for CBC were 47% and 30%; the survival difference seen between UBC and CBC patients was not statistically significant. The survival rates among younger, middle-aged and older women were significantly different from each other in UBC but not in CBC patients. Both UBC and CBC with early stage disease had a better survival compared to late stage disease. Survival advantage was also seen among both UBC and CBC patients with family history of breast cancer compared to those without. The multivariate analysis by the life table proportional hazards model showed that the age at diagnosis is an independent prognostic factor for breast cancer. The study results should be interpreted in the light of small sample size of second cancers.

Risk factors for contralateral breast cancer in Chennai (Madras), India

BACKGROUND

This is the first cohort study conducted in India to identify risk factors for contralateral breast cancer (CBC) among patients with first primary breast cancer.

METHODS

Patients with first primary breast cancer diagnosed in 1960-1989 at the Cancer Institute (WIA) in Chennai, India, were followed-up until 31 December 1994. The risk of CBC was assessed among unilateral breast cancer (UBC) patients who survived for >12 months following the diagnosis of breast cancer and did not develop a second cancer (n = 2665) and among those who developed a CBC > or =12 months after the diagnosis of breast cancer (n = 39).

RESULTS

The age-adjusted incidence of CBC among women with UBC was seven times the incidence (per single breast) in the general population. Among women with UBC the relative risk (RR) was 4.5 (95% CI: 1.1-19.6) comparing those with and without a history of breast cancer in the mother, and 2.8 (95% CI: 1.2-6.7) comparing age at first birth 21-25 versus earlier. The RR was 0.3 (95% CI: 0.1-0.6) comparing those with and without hormone therapy for their UBC. Radiotherapy for the UBC had no significant effect on the incidence of CBC.

CONCLUSION

Positive family history of breast cancer and later age at first childbirth emerged as stronger risk factors for CBC than UBC. Hormone therapy reduces the risk of CBC.

Registration of cancer mortality data in a developing area: Chennai (Madras, India) experience

OBJECTIVES

This study was carried out to evolve a method to improve the registration of cancer mortality data in Chennai (Madras, India).

METHODS

Data on cancer deaths have been collected from the Vital Statistics Department (VSD) by a population-based cancer registry (PBCR) in Chennai only since 1982. The low mortality-to-incidence ratio during 1982-84 suggested under-registration of mortality data. Since 1985, the PBCR has taken special effort to ascertain the vital status of cancer cases by sending reply-paid postcards and/or making house visits. The data on all deaths occurring in Chennai, irrespective of stated cause of death in the death certificate, have been collected from the VSD since 1992.

RESULTS

Deaths that occurred in Chennai and obtained by sending reply-paid postcards and/or making house visits were registered in VSD as non-cancer causes of death; hence, these data were not collected from VSD. The sensitivity and positive predictive values of death certificates on cancer diagnosis based on 1992 and 1993 mortality data were 57 percent and 99.5 percent, respectively.

CONCLUSION

Since the accuracy of death certificate information on cancer diagnosis is relatively low in a developing country such as in India, collecting data on all deaths will improve the mortality data registration in PBCRs.

A study on pancreatic cancer in Chennai (Madras), India

A total of 299 pancreatic cancer (PC) cases were registered in Chennai during 1982-1993 with an age-adjusted incidence rate (AAR) of 1.0 per 100,000. The present study shows an increasing trend in the risk of PC with an increase in the literacy level among males (P < 0.001). The relative survival rates at 1, 3 and 5 years were 35.7, 14.4 and 6.1%, respectively. Age at diagnosis, sex, religious group and literacy level did not emerge as significant prognostic factors for survival from PC. It is reiterated that emphasis should be placed on primary prevention of pancreatic cancer as opposed to early detection, by controlling the use of tobacco.

A population-based survival study on female breast cancer in Madras, India

Breast cancer is the second most common cancer among women in Madras and southern India after cervix cancer. The Madras Metropolitan Tumour Registry (MMTR), a population-based cancer registry, collects data on the outcome of cancer diagnosis by both active and passive methods. A total of 2080 cases of invasive female breast cancer were registered in MMTR during 1982-89. Of these, 98 (4.7%) cases were registered on the basis of death certificate information only (DCO), and there was no follow-up information for 235 (11.3%). These were excluded, leaving 1747 (84%) for survival analysis. The mean follow-up time was 43 months. The overall Kaplan-Meier observed survival rates at 1, 3 and 5 years were 80%, 58% and 48% respectively; the corresponding figures for relative survival were 81%, 61% and 51%. A multifactorial analysis of prognostic factors using a proportional hazards model showed statistically significant differences in survival for subjects in different categories of age at diagnosis, marital status, educational level and clinical extent of disease. Increasing age at diagnosis was associated with decreased survival. Single women displayed poorer survival (37.4%) at 5 years than those married and living with spouses (50.0%). The survival rate among those who had more than 12 years of education was higher (70%) at 5 years than that of illiterate subjects (47%). An inverse relationship was seen between survival rates and clinical extent of disease. The need for research to determine feasible public health approaches, allied to coordinated treatment facilities to control breast cancer in India, is emphasized.

Lifestyle and risk of stomach cancer: a hospital-based case-control study

BACKGROUND

Stomach cancer (SC) is the most frequent cancer among males and third most common cancer among females in Madras, India. The incidence rate of SC is higher in Southern India compared to Northern India.

METHODS

A hospital-based case-control study on 388 incident cases of SC was carried out in Madras as part of a multicentre study in India to identify the risk factors for SC. Cases were matched to cancer controls based on age (+/- 5 years), sex, religion and mother tongue. Categorical variables for income group, level of education and area of residence were included in all models to control for confounding.

RESULTS

Smokers had a twofold risk of SC (95% confidence interval [CI] = 1.25-3.78) compared to non smokers and the risk seen among current smokers (odds ratio [OR] = 2.5; 95% CI: 1.36-4.44) was significantly different from that seen among exsmokers (OR = 1.5; 95% CI: 0.67-3.54). The risk among those who smoke bidi (OR = 3.2; 95% CI: 1.80-5.67) was higher than that seen among cigarette (OR = 2.0; 95% CI: 1.07-3.58) and chutta (OR = 2.4; 95% CI: 1.18-4.93) smokers. Significant dose response relationships were observed with age began smoking bidi (P < 0.001) and with lifetime exposure to bidi (P < 0.001), cigarette (P < 0.01) and chutta (P < 0.05) smoking. The habits of drinking alcohol and chewing did not emerge as risk factors. An interaction effect was not seen between the lifestyle habits. Attributable risk (AR) for smoking among exsmokers was 33% and current smokers 60%. Population AR for smoking was 31%.

CONCLUSION

Smoking tobacco is an independent risk factor for SC.

Cervical cancer screening in Tamilnadu, India: a feasibility study of training the village health nurse

Uterine cervical cancer is the most common malignancy among females in developing countries, including India. The success of cervical cancer screening programs in North America and Western Europe has been the result of centralized cervical-cytology screening. This is not possible in the villages (n = 17,000) of Tamilnadu where 58 percent of females in rural areas are illiterate, health infrastructure is mediocre, and cervical cytology is unknown. The present study was undertaken to examine if the village health nurse (VHN) could be trained quickly to identify a cervical abnormality by visual inspection so that we could 'down stage' the cancer to earlier stages, more amenable to treatment. VHNs also would be trained to take an adequate Pap smear. A total of 101 VHNs were trained in batches and returned to their villages. Within two years, 6,459 eligible women in the study area were screened. The agreement between the gynecologists and the VHNs in identifying cancer among those with abnormal cervix was 95 percent, and 80 percent of the Pap smears taken by VHNs were adequate by WHO criteria, making the feasibility study highly successful.

Prognostic variables and survival in pediatric acute lymphoblastic leukemias: cancer institute experience

This presentation is an analysis of front-end prognostic variables in achieving a complete response, a continuous complete remission, and disease-free survival in pediatric acute lymphoblastic leukemia at the Cancer Institute, Madras, India between 1983 and 1988. The clinical characteristics at presentation showed that virtually 100% of patients belong to the poor risk category, age < 3 years of > 6 years 72.2%, WBC > 10,000/mm3 59.8%, blast count > 50% 39.2%, organomegaly 91.8%, and L2 morphology 66.0%. All patients had more than one risk factor. Between 1983 and 1988, 97 children were treated on a pilot protocol designed in collaboration with the Lymphoma Biology Division of the Pediatric Oncology Branch of the National Cancer Institute, Bethesda, Maryland. The protocol was designed for a poor prognostic group. The significance of implicated poor prognostic factors was analyzed using the Cox proportional hazard model. Age at presentation was the only variable that emerged as an independent risk factor, and sex appeared to be a modifier. No other variables attained significance. Survival data were calculated by the Kaplan-Meier method. The relapse-free and event-free survivals up to 10 years were 50.7% and 38.1%, and compare reasonably well with results reported for similar groups elsewhere for the same period.

Tobacco-related cancers in Madras, India

Tobacco is the single most important cause of avoidable morbidity and early mortality in many countries. Tobacco-related cancer (TRC) cases constitute 48.2% in men and 20.1% in women of the total cancers seen in India per year. The age-adjusted rate (AAR) of TRC ranges from 44 to 67 among males and from 23 to 27 among females in different registries in India. Of these cases, only 15% were in the lung. The religion-specific risk ratio of the TRC sites in Madras suggests that when Muslims were compared with Hindus pharynx and lung were the two sites that showed higher risk in males, while the pharynx, lung and oesophagus had higher risk in females. When Christians were compared with Hindus, lung cancer was found to have higher risk and cancer of the oesophagus lower risk in males, while cancer of the mouth had lower risk in females. The overall percentage increase in AAR of TRCs in males was 39.7 and in females was 20.1 for the period 1987-91, compared with 1982-86, with variation in the percentage increase in all the TRC sites in Madras. The change in the incident rate of TRCs seen in Madras is consistent with the change in the per capita consumption of tobacco over the years.

Methodology for long term follow-up of cancer cases in a developing environment

The utility of data collected on patients will be rendered insignificant without adequate follow-up information. Efficient methods should be used to follow cases in order to get vital status information in Hospital(HBCR) and Population Based Cancer Registries (PBCR). Based on our experience we have evolved methods to follow cancer cases and this has been discussed in this paper. Active follow up of cases has enhanced follow-up rate from 50% to more than 85% at HBCR and "death in period" from 19% to 41% during the period 1982 to 1991 in PBCR. Active follow-up is mandatory for the cases registered at HBCR. In addition to collecting data from VSD on cancer deaths, active follow-up is desirable to get maximum death information on cases registered at PBCR in a developing environment. Computerization of follow-up data is necessary in order to further improve the efficiency of the follow-up system.

Leukemia after irradiation for endometrial cancer in Ontario

BACKGROUND

In human studies, the risk of leukemia after ionizing radiation has been found to be increased more often than for any other cancer. It is useful to study patients with cancer treated with radiation because exposure can be measured accurately, follow-up may be long, and often a comparable and sizable nonexposed group exists. Women with endometrial cancer represent an excellent population for study because they meet these Developed Leukemia After Endometrial.

METHODS

A population-based matched case-control study, nested among all patients with endometrial cancer diagnosed in Ontario, was undertaken to describe the relationship between radiation therapy and leukemia risk. Among 13,843 subjects treated from 1964 to 1987 who survived at least 1 year, 47 confirmed cases of leukemia were identified. Four control subjects were matched to each patient based on age, calendar year of diagnosis, and length of survival free of a second neoplasm. Medical records were abstracted, and radiation dose administered to active bone marrow was determined by dosimetry.

RESULTS

An elevated risk of all leukemias other than chronic lymphocytic leukemia was observed, but only within the first 10 years after endometrial cancer treatment (odds ratio 12.0; 90% confidence interval 2.8-52.1). There was insufficient statistical evidence that risk was influenced by dose or type of radiation therapy. Nor was there any evidence that risk was influenced by age at endometrial cancer diagnosis or by calendar period at diagnosis.

CONCLUSIONS

There is an increased risk of leukemia associated with radiation therapy for patients with endometrial cancer, but only within the first 10 years after treatment.

Cancer registration in Madras Metropolitan Tumour Registry, India

The Madras Metropolitan Tumour Registry (MMTR) was established at the Cancer Institute (WIA), Madras, in 1981-1982. Cancer is not a notifiable disease in India, and hence registration per force has to be active. The MMTR covers a population of 3.8 million. Mortality statistics are obtained from the Department of Vital Statistics, death registers in hospitals and by active follow-up of registered cases. A total of 28,980 (13,012 males, 15,968 females) cases were registered during 1982-1991. The average annual world-standardised age-adjusted rates (AAR) per 100,000 are 104.2 in males and 129.0 in females. The lifetime cumulative risk (0-74 years) of cancer in Madras is one in eight. Stomach (AAR:15.2) is the leading site of malignancy among males, followed by cancers of the lung (AAR:9.8) and oral cavity (AAR:9.4). Among females, cancer of the cervix (AAR:44.0) is the commonest, followed by breast (AAR:21.7) and oral cavity cancers (AAR:9.8).

Association between cervical and penile cancers in Madras, India

A total of 4,995 cervical and 311 penile cancer cases were registered in the Madras Population-Based Cancer Registry at the Cancer Institute (WIA), Madras, India, in 1982-1990. The parameters analyzed were age at the time of diagnosis, educational level, marital status, and religion. Peak incidence of carcinoma of the cervix was seen in the age group 55-59 years. The incidence of penile cancer increased consistently with age. Among cervical cancer patients, the incidence was significantly higher among illiterates and among those who had an education for 12 years or less than among those with over 12 years of education. The incidence of cervical cancer was low among Muslim women compared to Hindu and Christian women, and penile cancer was not seen at all among Muslim men. Our results re-emphasize the importance of circumcision in the reduction of the risk of both cervical and penile cancers.

Risk factors for female breast cancer. A hospital-based case-control study in Madras, India

Five hundred and thirty-one histologically confirmed breast carcinoma cases examined from 1983 to 1986 inclusive at the Cancer Institute (WIA), Madras, India, were matched for age, socioeconomic class and menopausal status with an equal number of controls. Cancer patients without diseases in breast, gynaecological organs or endocrine glands were used as controls. Risk factors for breast cancer were analyzed separately in the premenopausal and the postmenopausal groups. In neither group was there significant association between age at menarche and breast cancer risk. Single women had higher risk than married women. Nulliparity was found to be a risk factor in premenopausal women only. The relative risk increased with age at marriage and age at first birth. A three-fold risk was noted in both pre- and postmenopausal groups when the interval between age at first birth and menarche was more than 12 years and also in women who attained menopause between the age of 44-49.