Socio-economic disparities in access to treatment and their impact on colorectal cancer survival.

BACKGROUND: Significant socio-economic disparities have been reported in survival from colorectal cancer in a number of countries, which remain largely unexplained. We assessed whether possible differences in access to treatment among socio-economic groups may contribute to those disparities, using a population-based approach. METHODS: We retrospectively studied 71 917 records of colorectal cancer patients, diagnosed between 1997 and 2000, linked to area-level socio-economic information (Townsend index), from three cancer registries in UK. Access to treatment was measured as a function of delay in receipt of treatment. We assessed socio-economic differences in access through logistic regression models. Based on relative survival < or =3 years after diagnosis, we estimated excess hazard ratios (EHRs) of death for different socio-economic groups. RESULTS: Compared with more affluent patients, deprived patients had poorer survival [EHR = 1.20; 95% confidence interval (CI) 1.16-1.25], were less likely to receive any treatment within 6 months [odds ratio (OR) = 0.87, 95% CI 0.82-0.92] and, if treated, were more likely to receive late treatment. No disparities in survival were detected among patients receiving treatment within 1 month from diagnosis. Disparities existed among patients receiving later or no treatment (EHR = 1.30; 95% CI 1.22-1.39), and persisted after adjustment for age and stage at diagnosis (EHR = 1.15; 95% CI 1.08-1.24). CONCLUSIONS: Tumour stage helped explain socio-economic disparities in colorectal cancer survival. Disparities were also greatly attenuated among patients receiving early treatment. Aspects other than those captured by our measure of access, such as quality of care and patient preferences in relation to treatment, might contribute to a fuller explanation.

Dental x-rays and the risk of thyroid cancer: a case-control study.

UNLABELLED: The thyroid gland is highly susceptible to radiation carcinogenesis and exposure to high-dose ionising radiation is the only established cause of thyroid cancer. Dental radiography, a common source of low-dose diagnostic radiation exposure in the general population, is often overlooked as a radiation hazard to the gland and may be associated with the risk of thyroid cancer. An increased risk of thyroid cancer has been reported in dentists, dental assistants, and x-ray workers; and exposure to dental x-rays has been associated with an increased risk of meningiomas and salivary tumours. METHODS: To examine whether exposure to dental x-rays was associated with the risk of thyroid cancer, we conducted a population-based case-control interview study among 313 patients with thyroid cancer and a similar number of individually matched (year of birth +/- three years, gender, nationality, district of residence) control subjects in Kuwait. RESULTS: Conditional logistic regression analysis, adjusted for other upper-body x-rays, showed that exposure to dental x-rays was significantly associated with an increased risk of thyroid cancer (odds ratio = 2.1, 95% confidence interval: 1.4, 3.1) (p=0.001) with a dose-response pattern (p for trend <0.0001). The association did not vary appreciably by age, gender, nationality, level of education, or parity. DISCUSSION: These findings, based on self-report by cases/controls, provide some support to the hypothesis that exposure to dental x-rays, particularly multiple exposures, may be associated with an increased risk of thyroid cancer; and warrant further study in settings where historical dental x-ray records may be available.

Some issues in screening for breast and other cancers.

BACKGROUND: There are some issues in screening for cancer, especially breast cancer, which are worthy of further study. METHODS: We reviewed some approaches to the following issues in breast cancer screening: absolute benefit, overdiagnosis, separation of effects of screening from effects of others on deaths from breast cancer over time and determination of which tumours benefit most from early detection. For separation of screening effects from other effects, we developed a simple analysis of survival by tumour size. For the other issues, we identified methods and results from the literature on the randomized trials of screening and on service screening programmes. We also reviewed screening issues pertaining to other selected cancers, including some cancers common or becoming common in Asia. RESULTS: Published results from the Swedish Two-County Trial showed that for 350 women screened for 10 years, one life would be saved. Results from service screening programmes in Florence and elsewhere suggested that overdiagnosis is a minor phenomenon and mainly confined to ductal carcinoma in situ. Data from before and after the inception of screening in East Anglia suggested that 40-60% of the recent improvement in survival of breast cancer cases was due to early detection. Published data from the Swedish Two-county Trial indicated that the majority of the benefit of breast screening derives from early detection of grades 2 and 3 ductal carcinoma. CONCLUSIONS: Mammographic screening is effective in saving lives from breast cancer. Other cancers, which have strong evidence for a benefit of screening in terms of saving lives from cancer, are cervical and colorectal cancers. There is also evidence of a reduction in mortality associated with ultrasound screening for liver cancer in subjects at very high risk of the disease. There are a number of other cancers that are potential candidates for early detection. There is clearly an opportunity for saving lives from further development and implementation of cancer screening.

Impact of false-positive mammography on subsequent screening attendance and risk of cancer.

BACKGROUND: One area of concern within the largely successful UK National Health Service breast screening programme is the relatively high proportion of women showing mammographic abnormalities who undergo further diagnostic tests that prove negative. Previous studies suggest that, in addition to increasing anxiety, such false-positive mammography is associated with increased risk of subsequent interval cancer. In the present article, we quantify this increased risk, investigate whether it extends to cancers detected at rescreening, and determine whether cancers differ between women who have, and have not, experienced false-positive mammography. METHODS: This was a retrospective cohort study of 140,387 women aged 49-63 years routinely invited for first screening by the East Anglian National Health Service breast screening programme. Proportions reattending, and subsequent risk and pathological attributes of cancer were compared between women who underwent further (negative) assessment following false-positive mammography and women mammographically normal at first screen. RESULTS: At first screen, 108,617 (91.9%) of the screened women were mammographically normal, 4278 (3.6%) were assessed and then judged normal, and 514 (0.4%) underwent benign biopsy. Compared with nonassessed normal women, reattendance was lower among assessed women: 83.1% (95% confidence interval [CI], 82.0-84.1) versus 85.7% (95% CI, 85.5-85.9) (odds ratio [OR], 0.82; 95% CI, 0.76-0.89). Assessed women were at greater risk of interval cancer (rate per 1000 women screened, 9.6 [95% CI, 6.8-12.4] versus 3.0 [95% CI, 2.7-3.4]; OR, 3.19 [95% CI, 2.34-4.35]), and also of cancer detected at second screen (rate per 1000, 8.4 [95% CI, 5.8-10.9] versus 3.9 [95% CI, 3.5-4.3]; OR, 2.15 [95% CI, 1.55-2.98]). More cancers in assessed women measured >or = 20 mm (OR, 1.59; 95% CI, 0.99-2.55). CONCLUSIONS: Women undergoing false-positive mammography at first screen were less likely to reattend for subsequent screens than were nonassessed women, yet they were more likely to develop interval cancers or cancers at second screen, and their cancers were larger. Factors predisposing for false-positive mammography require investigation. Women should be encouraged to continue with screening.