An overview of cancer survival in developing countries.
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Adolescent↗
Biomedical subjects
R Sankaranarayanan
Publications and source records attributed to R Sankaranarayanan.
[Population-based cancer survival: an analysis of 16,922 cases].
OBJECTIVE: In the period of 1982-1991, 16,922 patients with cancers from 15 sites of Qidong population-based cancer registry were analysed for evaluation of cancer survival as well as different cancer control measures. METHODS: Observed survival rate (OS) was computed by the Kaplan-Meier method using EGRET statistical software package. Relative survival (RS) which is the ratio of the OS to the expected rate was calculated by using Qidong life table with respect to sex, age and calendar period of observation. RESULTS: The five-year OS for the 5 leading sites of cancers, liver, stomach, lung, oesophagus, and rectum were 1.8%, 11.6%, 3.0%, 3.3%, and 19.9%, respectively. The five-year RS for the 5 sites were 1.9%, 14.0%, 3.6%, 4.2%, and 23.7%, respectively, in which, 1.7%, 14.8%, 3.4%, 4.2%, and 26.0% for males, and 2.7%, 12.7%, 4.1%, 4.0%, and 22.0% for females, respectively. Female patients with breast cancer and cervix cancer had 5-year RS of 54.6% and 33.0%. CONCLUSION: Cancer survival rates for all sites are poor, in which that of the liver is the lowest, while that of the breast, the highest. The survivals of cancers for all sites, especially for breast, cervix, and leukaemia are seen to be lower than those of European countries except for oesophagus, pancreas and lung cancer which do not achieve improved survival both in developing and developed countries. There will be a long way to improve the total cancer survival, as well as the cancer treatment in the developing countries.
Adolescent↗
Radiotherapy in the treatment of verrucous carcinoma of the oral cavity.
Verrucous carcinomas are considered to have poor radioresponsiveness and radiotherapy has been reported to induce anaplastic transformation. Surgery has been considered to be the primary mode of treatment for these tumours. The clinical features, response to radiotherapy, survival and prognostic factors of a group of 53 patients with oral verrucous cancers, were studied and compared to patients with oral well-differentiated, squamous cancers, treated during the same time period. The buccal mucosa was the commonest primary site in both groups. 42 patients with verrucous cancer underwent primary radiotherapy and 11 underwent primary surgery. Complete response to radiotherapy was achieved in 76% of patients with verrucous cancer and partial response in 24%. Patients with verrucous cancer had a five year actuarial disease-free survival of 66% and overall survival of 86%. The corresponding survival figures were 43% and 56% in well-differentiated squamous cancers (P = 0.004). Composite stage of disease was a significant predictor of disease-free survival in both groups. None of the 16 patients with verrucous cancers that recurred after radiotherapy, had features of anaplastic transformation. Oral verrucous carcinoma appears to have similar radioresponsiveness and improved disease-free survival, compared to well-differentiated squamous cancers. The treatment policies for other oral squamous cancers are applicable to these tumours.
Adult↗
Chemoprevention of oral leukoplakia with vitamin A and beta carotene: an assessment.
We conducted a double-blind placebo-controlled trial to evaluate the chemopreventive potential of either vitamin A alone or beta carotene alone in subjects with oral leukoplakia in Kerala, India. We randomised 160 fishermen and women with oral precancerous lesions to receive oral vitamin A (retinyl acetate 300,000 IU/week x 12 months, n = 50), or beta carotene (360 mg/week x 12 months, n = 55), or placebo (n = 55). Blood, saliva and urine samples were collected at baseline and at exit to study serum micronutrients and mutagenicity assays. Biopsies of the mucosal lesions at entry were performed for histopathological exclusion of malignancy. The subjects were examined once every 2 months to establish clinical response of lesions and toxicity, if any. The results are based on 43 complaint subjects on placebo, 42 on vitamin A and 46 on beta carotene. The complete regression rates were: 10% in the placebo arm, 52% with vitamin A and 33% with beta carotene (P < 0.0001). Homogeneous leukoplakias and smaller lesions responded better than non-homogeneous and larger lesions. No major toxicities were observed. Half of the responders with beta carotene and two thirds with vitamin A relapsed after stopping supplementation. Serum beta carotene concentration increased substantially with beta carotene administration while with vitamin A supplementation there was no change in serum retinol levels. In the vitamin A treated group there was a significant decrease in serum alpha tocopherol. Vitamin A administration resulted in a significant remission of oral leukoplakia without any side effects of prolonged vitamin A supplementation. The results of this study, as well as those from previous studies, appear to provide strong supporting evidence to justify long term trials with vitamin A in subjects with high-risk leukoplakias with oral cancer as an endpoint.
Adult↗
Health care auxiliaries in the detection and prevention of oral cancer.
Oral cancer is one among the few human cancers with a vast potential for prevention. One of the operational strategies considered to translate preventive measures into practice in developing countries has been the use of community health workers and other health auxiliaries of the primary health care system to disseminate anti-tobacco health education messages and to provide mouth examinations in high-risk individuals during their routine home visits and community meetings. Studies conducted in India and Sri Lanka to address the role of the above approach indicate that it is feasible to train community health workers and other health auxiliaries in primary prevention and early detection of oral cancer and precancerous lesions. However, no evidence of the efficacy of such an approach in reducing the incidence and mortality from oral cancer is yet available. Sufficient evidence in terms of efficacy and cost effectiveness is needed to justifiably convince health administrators for the inclusion of non-communicable disease control in general and oral cancer screening in particular as part of the primary health care delivery by community health workers and other health auxiliaries especially when considering the burden of already existing work responsibilities. The need for studies in this direction is very obvious. However, the opportunities for 'case-finding' and health education should be utilised when encountering high-risk subjects both in primary medical and health care.
Community Health Workers↗
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.
Adult↗
Reproducibility and validity of oral visual inspection by trained health workers in the detection of oral precancer and cancer.
A randomized intervention trial is in progress in Kerala, India, to evaluate the effectiveness of oral visual inspection by trained health workers (HWs) in the prevention of oral cancer. Fourteen health workers with college graduation as the basic qualification were trained in oral visual inspection to identify oral cancers and precancers among the participants of the screening trial and to refer them for further confirmation and management. The aim of the present study was to evaluate the reproducibility and validity of the screening test provided by the health worker against the reference oral visual findings of three physicians. A total of 2069 subjects who had already been examined were re-examined by the health workers and physicians. The sensitivity and the specificity of the oral visual inspection were 94.3% and 99.3% respectively. There was moderate agreement between the findings of the initial and the repeat mouth examinations carried out by the health workers, which were on average 6 months apart. There was almost perfect agreement (kappa = 0.85) between the findings of the health workers and the physicians in identifying the different types of oral precancerous lesions. The findings of our study indicate that it is possible to train resource persons to perform the oral cancer screening test as accurately as doctors, although experience appears to be a crucial component of health workers' accuracy. The efficacy of such an approach to reduce the incidence of and mortality from oral cancer, however, remains to be proven.
Education↗
Evaluation of visual inspection as a screening test for cervical cancer.
Visual inspection of the uterine cervix by paramedical personnel has been proposed for the early detection of cervical cancer, as an alternative to routine cytology screening in developing countries. We evaluated the performance of this procedure in detecting precursor lesions and cancer in a study involving 2843 married women in Kerala, India. Two thresholds were used to define a positive test. In the lower one, any abnormality was considered as positive. The cut-off point for the high threshold was one or more of the high-risk findings: bleeding on touch, suspicious growth/ulcer and hard, irregular, oedematous cervix. A Pap smear was performed on all subjects, and a biopsy was done for those with moderate dysplasia and above. A combination of cytology and histology findings was used as the 'gold standard'. Using the low threshold, 1279 (45%) women were positive on visual inspection, and with the higher threshold 179 (6.3%) were positive. There were six moderate dysplasias, nine severe dysplasias, ten carcinomas in situ and 13 invasive carcinomas. With the lower threshold, sensitivity and specificity to detect moderate dysplasia and above were 65.8% and 55.3% respectively; the values for severe dysplasia and above were 71.9% and 55.3% respectively and for invasive cancer were 92.3% and 55.2% respectively. With the higher threshold, the sensitivity decreased considerably (28.9% to detect moderate dysplasia lesions, 31.3% for severe dysplasia and 53.8% for clinical cancer) and the specificity increased to approximately 94%. At a lower threshold, the sensitivity was not satisfactory, and the test was highly non-specific; at a higher threshold sensitivity was even lower. Thus, the test characteristics of visual inspection are not very promising either as a preselection procedure for cytology or as a low-technology measure for cervical cancer screening in developing countries.
Adult↗
Evaluation of multiple micronutrient supplementation in the management of oral submucous fibrosis in Karachi, Pakistan.
Oral submucous fibrosis (OSF) is an oral precancerous condition characterized by symptoms such as intolerance to spicy food, altered salivation, progressive difficulty in opening the mouth, and signs like vesiculation, ulceration, blanching, rigidity, and stiffening of the oral mucosa and depapillation and altered mobility of the tongue. It is seen mostly among people of Indian subcontinent origin. The major structural change is extensive fibroelastic scarring of the lamina propria and deeper connective tissues. A combination of micronutrients (vitamins A, B complex, C, D, and E) and minerals (iron, calcium, copper, zinc, magnesium, and others) was evaluated for its efficacy in controlling the symptoms and signs of OSF in 117 compliant subjects in Karachi, Pakistan, in a single-arm preliminary study. The subjects received supplementation for one to three years. Significant improvement in symptoms, notably intolerance to spicy food, burning sensation, and mouth opening, was observed at exit. The interincisor distance deteriorated in 11 subjects (10%) at exit; it was stable in 56 subjects (49%) and improved in 48 (41%). The mean interincisor distance was 19.1 +/- 10.8 (SD) mm at exit compared with 16.2 +/- 7.5 mm at baseline. A significant proportion of concomitant lesions like leukoplakia also regressed at exit. The major outcome from this study was a beneficial clinical response in subjects with OSF to multiple micronutrient intervention, which justifies its further evaluation in well-designed randomized controlled trials in other settings in South Asia.
Adolescent↗
Global variations in cancer survival. Study Group on Cancer Survival in Developing Countries.
Population-based cancer registries from Algeria, China, Costa Rica, Cuba, India, the Philippines, and Thailand are collaborating with the International Agency for Research on Cancer in a study of cancer survival in developing countries. Comparisons with the SEER program results of the National Cancer Institute in the United States, and the EUROCARE study of survival in European countries revealed considerable differences in the survival of patients with certain tumors associated with intensive chemotherapeutic treatment regimes (Hodgkin's disease and testicular tumors), more modest differences in the survival of patients with tumors for which early diagnosis and treatment confer an improved prognosis (carcinomas of the large bowel, breast, and cervix), and only slight differences for tumors associated with poor prognosis (carcinomas of the stomach, pancreas, and lung). With limited resources to meet the challenge of the increasing incidence of cancer expected in the next few decades, health authorities in developing countries should be aware of the importance of investing in a range of cancer control activities, including primary prevention and early detection programs as well as treatment.
Developed Countries↗
Early detection of cervical cancer by visual inspection: a population-based study in rural India.
A total of 3784 women aged 35 and above living in 26 villages in rural Maharashtra state, India, were invited to undergo a pelvic examination, to evaluate the performance of unaided visual inspection by trained paramedical workers in detecting cervical cancer. Of this number, 2135 (56.4%) women complied with the invitation. Paramedical workers scored 1120 (57.3%) and 118 (6%) women as having abnormal cervices using the low- and high-threshold criteria respectively. There was good agreement between the visual findings of the paramedical workers and those of a gynaecologist. All subjects had a cervical smear. A total of 10 cervical cancers were detected by cytology/histology. The sensitivity of visual inspection by paramedical workers to detect cervical cancer was 90.0% using the low threshold and 60.0% with the high threshold to define a positive test. The values for specificity were 42.8% and 94.5% respectively. The results obtained by the gynaecologist were very similar. Cost savings implied by limiting cytology/other investigations to approximately half of the population pre-selected on the basis of visual inspection are likely to be offset by the necessity to repeat the test at frequent intervals, repeated follow-up visits and other investigations.
Adult↗
Evaluation of inter-incisor distance as an objective criterion of the severity of oral submucous fibrosis in Karachi, Pakistan.
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Adult↗
Efficacy of vitamin A in the prevention of loco-regional recurrence and second primaries in head and neck cancer.
Chemoprevention with retinoids is currently an experimental approach to prevent local relapses and second primaries in treated head and neck cancer patients. We evaluated the effectiveness of vitamin A in preventing the above events in a randomised trial involving 106 head and neck cancer patients who had achieved complete regression of their disease with radiotherapy and/or surgery. They were randomised to receive retinyl palmitate (200,000 IU per week for 1 year) or placebo. 50 subjects on vitamin A and 43 on placebo completed 1 year supplementation; 49 in the former group and 42 in the latter could be evaluated over a 3 year period from the initiation of the study. One fifth (11/56) of patients in the vitamin A group and one tenth (5/50) in the placebo group had loco-regional recurrence. The frequency of recurrences in stage I patients in the vitamin A group was higher compared to the placebo group, although it was not statistically significant. No second primaries were observed in the vitamin A group; 2 patients in the placebo group had second primaries. No clinically obvious side effects were observed with vitamin A. The higher frequency of recurrences in the vitamin A group is of concern although it may be a chance finding given the small size of the trial. The effect on second primaries is consistent with other observations reported in literature.
Anticarcinogenic Agents↗
A novel mode of carbohydrate recognition in jacalin, a Moraceae plant lectin with a beta-prism fold.
Jacalin, a tetrameric two-chain lectin (66,000 Mr) from jackfruit seeds, is highly specific for the tumour associated T-antigenic disaccharide. The crystal structure of jacalin with methyl-alpha-D-galactose reveals that each subunit has a three-fold symmetric beta-prism fold made up of three four-stranded beta-sheets. The lectin exhibits a novel carbohydrate-binding site involving the N terminus of the alpha-chain which is generated through a post-translational modification involving proteolysis, the first known instance where such a modification has been used to confer carbohydrate specificity. This new lectin fold may be characteristic of the Moraceae plant family. The structure provides an explanation for the relative affinities of the lectin for galactose derivatives and provides insights into the structural basis of its T-antigen specificity.
Amino Acid Sequence↗
Chemoprevention of cancers of the oral cavity and the head and neck.
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Anticarcinogenic Agents↗
Retinoids as cancer-preventive agents.
Vitamin A and its metabolites play a crucial role in regulating the differentiation and proliferation of epithelial cells, and are potent inducers of apoptosis. The effects of retinoids are thought to be mediated through the metabolite retinoic acid, which binds to nuclear retinoic acid receptors that then interact with specific retinoic acid response elements. The development of cancers involves alterations in growth and differentiation of cells as a result of carcinogen-induced damage to DNA of regulatory genes. Most of the results from experimental animal studies indicate that retinoids are effective in preventing or suppressing cancers. Although the relationship between preformed vitamin A in the diet and epithelial cancers remains to be further clarified, a high intake of vegetables and fruits has been consistently associated with a lower risk of these cancers. This interesting biological activity profile of retinoids has prompted investigators to study them in the chemoprevention of epithelial cancers and in the treatment of advanced cancers. Although the therapeutic response of retinoids against advanced cancers is disappointing, they have emerged as promising chemopreventive agents, particularly in head and neck sites. Both natural and synthetic analogues of vitamin A have been shown to be effective in suppressing micronucleated cells, reversing oral leukoplakia, and preventing new and recurrent lesions in subjects with oral leukoplakia, as well as in reducing the occurrence of second primaries in treated head and neck cancer patients. They have not been consistently effective in suppressing either bronchial atypia or metaplasia, nor have they been proven effective in reducing the occurrence of recurrent lesions in treated skin cancer patients, although some activity has been demonstrated in reducing lesion counts in actinic keratoses. Vitamin A in combination with other micronutrients has not reduced incidence and mortality from oesophageal and stomach cancers. A synthetic retinoid, fenretinide, is currently being evaluated in preventing contralateral breast cancer in treated breast cancer patients. Toxicity has been a major concern with retinoids, as prolonged administration is required in chemoprevention studies. Available evidence indicates that natural analogues of retinoids are less toxic than synthetic compounds such as isotretinoin. Large studies are currently evaluating retinoids in the prevention of head and neck cancers and lung cancers. The outcome of these studies will be important in directing future research initiatives and in forming policies regarding the use of vitamin A compounds in the prevention of cancers.
Anticarcinogenic Agents↗
Cancer in Gabon, 1984-1993: a pathology registry based relative frequency study.
A pathology based cancer registry was established in 1977 in the pathology department of the faculty of health sciences of the University of Omar Bongo in Librevile, Gabon, which is the only pathology service catering to the needs of the population of approximately 1 million of Gabon. Analysis of the histologically diagnosed cancers during 1984 through 1993 revealed 1,367 male and 1,235 female cases. The leading sites in males were: skin (11.0%), liver (8.9%), non-Hodgkin's lymphoma (8.7%), prostate (7.8%), lung (6.9%), mouth (4.9%) and tongue (4.7%). The predominant sites in females were: uterine cervix (26.3%), breast (13.9%), non-Hodgkin's lymphoma (7.1%), skin (5.1%), liver (3.9%) and ovary (3.3%). Considering the little information available on cancer patterns in Africa, even relative frequency data for different periods from different sources are of considerable interest. We propose to establish population based cancer registration in Libreville (pop 400,000) where 40% of the national population lives, in the near future, which should provide reliable information on the cancer burden and patterns in Gabon.
Adolescent↗
Cancer survival in Khon Kaen Province, Thailand.
Thailand is one of the few developing countries for which population-based cancer survival data are available. Using clinical follow-up information and reply-paid postal enquiries, 10,333 residents of Khon Kaen province registered with cancer in the period 1985-1992 were followed-up to the end of 1993. The sites of the most common cancers in the province were liver (5-year relative survival rate 9.2%), cervix (60.1%), lung (15.4%), breast (48.1%) and large bowel (41.9%). Results for Khon Kaen were compared with age-standardized survival data for the US and Scotland. Survival was consistently higher for US whites compared to Khon Kaen residents for those cancers whose prognosis is associated with early diagnosis (breast, cervix and large bowel) or the availability of intensive therapy (leukaemia and lymphoma). The main implication of these results for cancer control in Thailand is that the interventions of greatest potential benefit are those designed to promote early detection. More than one-third of all cancers in Thailand are liver tumours: primary prevention through control of hepatitis-B infection and liver fluke infestation is the only effective strategy for their control.
Adult↗