A centrally generated primary care physician audit report does not improve colonoscopy uptake after a positive result on a fecal occult blood test in Ontario's ColonCancerCheck program.

BACKGROUND: Timely follow-up of fecal occult blood screening with colonoscopy is essential for achieving colorectal cancer mortality reduction. In the present study, we evaluated the effectiveness of centrally generated, physician-targeted audit and feedback to improve colonoscopy uptake after a positive fecal occult blood test (fobt) result within Ontario's population-wide ColonCancerCheck Program. METHODS: This prospective cohort study used data sets from Ontario's ColonCancerCheck Program (2008-2011) that were linked to provincial administrative health databases. Cox proportional hazards regression was used to estimate the effect of centralized, physician-targeted audit and feedback on colonoscopy uptake in an Ontario-wide fobt-positive cohort. RESULTS: A mailed physician audit and feedback report identifying individuals outstanding for colonoscopy for 3 or more months after a positive fobt result did not increase the likelihood of colonoscopy uptake (hazard ratio: 0.95; 95% confidence interval: 0.79 to 1.13). Duration of positive fobt status was strongly inversely associated with the hazard of follow-up colonoscopy (p for linear trend: <0.001). CONCLUSIONS: In a large population-wide setting, centralized tracking in the form of physician-targeted mailed audit and feedback reports does not improve colonoscopy uptake for screening participants with a positive fobt result outstanding for 3 or more months. Mailed physician-targeted screening audit and feedback reports alone are unlikely to improve compliance with follow-up colonoscopy in Ontario. Other interventions such as physician audits or automatic referrals, demonstrated to be effective in other jurisdictions, might be warranted.

Multistate transitional models for measuring adherence to breast cancer screening: A population-based longitudinal cohort study with over two million women.

Objective Prior work on the disparities among women in breast cancer screening adherence has been methodologically limited. This longitudinal study determines and examines the factors associated with becoming adherent. Methods In a cohort of Canadian women aged 50-74, a three-state transitional model was used to examine adherence to screening for breast cancer. The proportion of time spent being non-adherent with screening was calculated for each woman during her observation window. Using age as the time scale, a relative rate multivariable regression was implemented under the three-state transitional model, to examine the association between covariates (all time-varying) and the rate of becoming adherent. Results The cohort consisted of 2,537,960 women with a median follow-up of 8.46 years. Nearly 31% of women were continually up-to-date with breast screening. Once a woman was non-adherent, the rate of becoming adherent was higher among longer term residents (relative rate = 1.289, 95% confidence interval 1.275-1.302), those from wealthier neighbourhoods, and those who had an identifiable primary care provider who was female or had graduated in Canada. Conclusion Individual and physician-level characteristics play an important role in a woman's adherence to screening. This work improves the quality of evidence regarding disparities among women in adherence to breast cancer screening and provides a novel methodological foundation to investigate adherence for other types of screening, including cervix and colorectal cancer screening.

Annual surveillance mammography after early-stage breast cancer and breast cancer mortality.

BACKGROUND: After treatment for early-stage breast cancer (bca), annual surveillance mammography (asm) is recommended based on the assumption that early detection of an invasive ipsilateral breast tumour recurrence or subsequent invasive contralateral primary bca reduces bca mortality. METHODS: We studied women with unilateral early-stage bca treated by breast-conserving surgery from 1994 to 1997 who subsequently developed an ipsilateral recurrence or contralateral primary more than 24 months after initial diagnosis, without prior regional or distant metastases. Annual surveillance mammography was defined as 2 episodes of bilateral mammography 11-18 months apart during the 2 years preceding the ipsilateral recurrence or contralateral primary. The association between asm and bca death was evaluated using a Cox proportional hazards model. RESULTS: We identified 669 women who experienced invasive ipsilateral recurrence (n = 455) or a contralateral primary (n = 214) at a median interval of 53 months [interquartile range (iqr): 37-72 months] after initial diagnosis, 64.7% of whom had received asm during the preceding 2 years. The median interval between the 2 bilateral mammograms was 12.3 months (iqr: 11.9-13.0 months), and the median interval between the 2nd mammogram and histopathologic confirmation of ipsilateral recurrence or contralateral primary was 1.5 months (iqr: 0.8-3.9 months). Median followup after ipsilateral recurrence or contralateral primary was 7.76 years (iqr: 3.68-9.81 years). The adjusted hazard ratio for bca death associated with asm was 0.86 (95% confidence limits: 0.63, 1.16). CONCLUSIONS: Annual surveillance mammography was associated with a modestly lowered hazard ratio for bca death.

The association between visiting a primary care provider and uptake of periodic mammograms as women get older.

OBJECTIVE: To determine whether visits to a primary care provider (PCP) are associated with the uptake of periodic mammograms as women get older. METHODS: The cohort consisted of 2,389,889 women resident in Ontario, Canada, aged 50 to 79 at any point from 2001 to 2010, who were cancer-free and eligible for the Ontario Health Insurance Plan prior to study entry. Non-parametric estimation was used to describe the mean cumulative number of periodic mammograms for women with and without recent exposure to a PCP, as a function of age. Using age as the time scale, a recurrent event regression model was also implemented to examine the association between exposure to a PCP and rate of periodic mammograms, adjusted for income quintile and comorbidity. RESULTS: The mean observation window was 7.0 years. Uptake of periodic mammograms was significantly higher for women with recent exposure to a PCP compared with those without. This trend remained consistent as women aged, and the magnitude of the association increased for women aged 65 or older. The relative rate of periodic mammograms was lower than 1 and consistently decreased as women from lower income quintiles were compared with women from the wealthiest quintile. CONCLUSION: Visits to a PCP play an important role in uptake of periodic mammograms, and this association increases as women age.

Prevalence of screening in patients newly diagnosed with colorectal cancer in Ontario.

OBJECTIVES: The primary objective was to determine the proportion of individuals with a new diagnosis of colorectal cancer (CRC) in Ontario in whom the cancer was screen detected. The secondary objectives were to determine the cancer stage at diagnosis and the indications for the procedure in patients who received their first colonoscopy. PATIENTS AND METHODS: Individuals admitted to a hospital with a new diagnosis of CRC were randomly selected after stratifying by hospital type (teaching or community). The Canadian Institute for Health Information's Discharge Abstract Database was used to identify individuals with a first diagnosis of CRC during calendar year (CY) 2000, and Ontario Health Insurance Plan data were used to identify people 50 to 74 years of age who had their first colonoscopy during CY 2000. Up to 20 individuals were selected for each group (CRC or colonoscopy) in each of seven randomly selected community hospitals and three randomly selected teaching hospitals. Data were abstracted from the hospital charts. RESULTS: The hospital charts of 152 patients with a new diagnosis of CRC were examined. Of the 133 patients in whom screening status could be determined, eight had screen-detected cancers (6.0%). Of the 99 patients (65% of the sample) in whom stage could be determined, 43 (43.4%) had advanced disease (tumour-node-metastasis stage III or IV) at diagnosis. The hospital charts of 184 patients who underwent their first colonoscopy were examined. Of the 175 patients in whom the indication for colonoscopy could be determined, 45 underwent the procedure for screening purposes, 10 were for diagnostic workup of anemia and 120 for evaluation of symptoms. CONCLUSIONS: The low proportion (6%) of screen-detected CRC and the high proportion of patients (43.4%) with advanced disease at diagnosis reflect the lack of an organized screening program.

Socioeconomic status & returning for a second screen in the Ontario breast screening program.

In a retrospective cohort study involving 57902 women initially screened between January 1, 1995 and December 31 1997 by the Ontario Breast Screening Program (OBSP), we examined the relationship between geographically derived socioeconomic status (SES) and returning for a second screen. We controlled for age, rurality, preferred language, initial mammography results, previous mammography history, and referral by a health professional. Although SES was related to returning, rurality was an effect modifier of this relationship, a finding not previously reported. Compared to women in the highest ('richest') quintile, urban women in the first and second quintile were less likely to return; this relationship was not found in rural women. Low SES women, particularly in urban areas, should be specifically targeted to increase their likelihood of re-attendance for breast cancer screening within an organized program.

Evolution of treatment for Hodgkin's disease: a population-based study of radiation therapy use and outcome.

AIM: To examine changes in radiotherapy (RT) use, cause-specific survival (CSS), and overall survival (OS) in a population-based cohort of Hodgkin's disease (HD) patients diagnosed from 1982 to 1996. MATERIALS AND METHODS: Adult patients with HD diagnosed from 1 January 1982 to 31 December 1996 (n = 3957) were identified from the Ontario Cancer Registry. The cohort was divided into three consecutive 5-year periods: 1982-1986, 1987-1991, and 1992-1996. RT use, CSS and OS in each of these three periods were compared. For the entire cohort, the cumulative incidence of different causes of death was calculated. RESULTS: The proportion of patients receiving RT within 11 weeks of diagnosis declined over the three consecutive periods (25.1%, 15.6%, 11.7%, P < 0.001), as did the proportion receiving RT within 45 weeks (57.0%, 51.0%, 48.1%; P < 0.001). There was a significant increase in 5-year CSS over time (81%, 87%, 89%; P < 0.001), and OS (72%, 77%, 82%; P < 0.001), which remained significant in multivariable analyses. The cumulative incidence of death from causes other than HD was equal to the incidence of HD-related death within 12 years of diagnosis. CONCLUSIONS: There was a significant decline in the use of RT as the primary treatment modality and as part of the initial management of HD from 1982-1996 in Ontario. A greater proportion of patients received their RT after a delay consistent with the receipt of prior chemotherapy. There was also a significant increase in the CSS and OS over this period. These findings are in keeping with the adoption of effective chemotherapy in the treatment of HD.

Trends in hormonal management of prostate cancer: a population-based study in Ontario.

OBJECTIVE: To provide a population-based description of current practice in the use of hormonal management of prostate cancer. DESIGN,SETTING & PARTICIPANTS: All men in Ontario, Canada, age 65 and older, with confirmed prostate cancer starting maintained hormonal therapy, from July 1992 through December 1998 (11,435 patients). Data sources included the provincial drug benefit plan, hospital services data, and Ontario Cancer Registry. OUTCOME MEASURES: Rates and trends in the use of: surgical or medical castration; total androgen blockade (TAB); and monotherapies based on steroidal or nonsteroidal antiandrogens. RESULTS: In 5.5 years, use of 'standard' therapy based on surgical or medical castration alone dropped from 36% to 26% of patients, while the use of TAB doubled from 22% to 41%. Approximately 15% of patients received nonsteroidal antiandrogens without evidence of therapy aimed at central androgen blockade. Marked regional differences were observed and not explained by patient age or practitioner specialty. CONCLUSIONS: New hormonal therapies for prostate cancer have implications in terms of disease control, patient survival, side effects, and costs. Rapid growth in prescribing of antiandrogens may represent an unnecessary expense for public or private payers, and observed regional differences likely reflect lack of consensus on the relative merit of TAB. Patients and practitioners must have current information on the advantages and disadvantages of different therapeutic options, and quality-of life, particularly with respect to emerging drug therapies.

The management and outcome of bladder carcinoma in Ontario, 1982-1994.

BACKGROUND: To the authors' knowledge no previous study has described the management and outcome of bladder carcinoma on a population-based level. The objective of the current study was to describe the characteristics, treatment, and outcome of newly diagnosed invasive bladder carcinoma (n = 20,822) reported in Ontario, Canada between 1982-1994. METHODS: Electronic records of invasive bladder carcinoma (International Classification of Diseases code 188) from the Ontario Cancer Registry were linked to surgical and radiotherapy (RT) records. Bivariate and multivariate techniques were used to assess variations in the use of initial cystectomy and pelvic RT. The authors modeled the likelihood of death after diagnosis and the probability of cystectomy free survival. All analyses were controlled for age, gender, histology, and year of diagnosis. RESULTS: The most common histologic type was papillary transitional cell carcinoma. Maximum initial treatment was comprised of total cystectomy (5.1%), partial cystectomy or open excision (3. 5%), pelvic RT (5.9%), transurethral resection of the bladder (66. 7%), or lesser or no procedures (18.7%). The use of total cystectomy and pelvic RT varied among the regions of Ontario. Overall 5-year survival was 58.8%, and was 86.5% for patients with papillary histology. In multivariate analysis, although survival was similar among the regions, the relative risk of cystectomy conditional on survival varied. CONCLUSIONS: Papillary tumors portend a better survival than nonpapillary tumors. Variations in the use of total cystectomy and in the use of pelvic RT among the regions of Ontario did not appear to be associated with variations in survival. However, cystectomy free survival appeared to vary among the regions. These results suggest that patients can be managed safely using a bladder-preserving approach.

Association between age and the utilization of radiotherapy in Ontario.

PURPOSE: The purpose of this study was to assess whether: (i) radiotherapy (RT) utilization varies with age in Ontario cancer patients; (ii) age-associated differences in the use of RT (if they exist) vary with cancer site and treatment intent; (iii) the age-associated variation in RT utilization is comparable to the decline in functional status in the general population; and (iv) the variation with age is due to differences in referral to a cancer center or to subsequent decisions. METHODS AND MATERIALS: Details for several cancer sites diagnosed between 1984-1994 were obtained from the Ontario Cancer Registry (OCR). RT records from all treatment centers were linked to the OCR database. Information about the functional status of the Canadian population was obtained from the 1994 National Population Health Survey conducted by Statistics Canada. RESULTS: The rate of RT use declined with age, particularly for adjuvant and palliative indications. The relative decline in RT with age exceeded the relative decline in functional status with age in the general population. Most of the decline in RT use was related to a decline in referral to cancer centers. CONCLUSIONS: The referral for, and use of, palliative and adjuvant RT decreases more with age than can be explained by age-associated decline in functional status observed in the general population.

A population-based study of the effectiveness of breast conservation for newly diagnosed breast cancer.

PURPOSE: Our objective was to evaluate the effectiveness of breast conservation for newly diagnosed breast cancer. Effectiveness was operationalized as two outcomes within 5 years of the diagnosis of breast cancer: the probability of mastectomy-free survival (either death or mastectomy count as event, whichever comes first), and the probability of mastectomy conditional on survival (mastectomy counts as event, observations censored at death). METHODS AND MATERIALS: We linked records of 46,687 new cases of breast cancer from 1982 to 1991 in the Ontario Cancer Registry to records of surgery from 1982 to 1995, radiotherapy (RT) from 1982 to 1992, and median household income from the 1986 census. We labeled breast surgery within 4 months and postoperative RT within 12 months of diagnosis as treatment for newly diagnosed breast cancer. Surgery was categorized as mastectomy, lumpectomy plus RT, lumpectomy alone, or no surgical procedure. Among cases that did not undergo mastectomy within 4 months of diagnosis, we labeled mastectomy subsequent to 4 months after diagnosis as treatment failure. We performed life-table analysis and Cox proportional hazards regression, to describe the probability of mastectomy conditional on survival and the probability of mastectomy-free survival. RESULTS: A total of 16,279 cases underwent lumpectomy as the maximum procedure on the breast within 4 months of diagnosis, and 49.7% of these received postoperative RT. Compared to the provincial mean, regions with higher rates of lumpectomy plus RT have higher probability of mastectomy-free survival and lower probability of mastectomy conditional upon survival 5 years after diagnosis of breast cancer. CONCLUSIONS: These findings are consistent with a hypothesis that breast conservation is effective in the overall breast cancer population of Ontario within the first 5 years after diagnosis.

A population-based study of rectal cancer: permanent colostomy as an outcome.

PURPOSE: The objectives of this study are to describe the utilization of surgery and of radiotherapy in the treatment of newly diagnosed rectal cancer in Ontario between 1982 and 1994, and to describe the probability of permanent colostomy at any time after the diagnosis of rectal cancer, as an outcome of the treatment of newly diagnosed rectal cancer. METHODS AND MATERIALS: Electronic records of rectal cancer (International Classification of Diseases code 154) from the Ontario Cancer Registry (n = 18,695, excluding squamous, basaloid, cloacogenic, and carcinoid histology) were linked to surgical records from all Ontario hospitals, and radiotherapy (RT) records from Ontario cancer centers. Procedures occurring within 4 months of diagnosis, or within 4 months of another procedure for rectal cancer, were considered part of initial treatment. Multivariate analyses controlled for age, sex, and year of diagnosis. RESULTS: Resection plus permanent colostomy was performed in 33.1% of cases, whereas local excision or resection without permanent colostomy was performed in 38.2%. Multivariate logistic regression demonstrated higher odds ratios (OR) for resection plus permanent colostomy in all regions of Ontario relative to Toronto. The OR for postoperative RT following local excision or resection without permanent colostomy varied among the regions relative to Toronto (e.g., OR Ottawa = 0.59, OR Hamilton = 0.76, OR London = 1.25). The relative risk (RR) of colostomy conditional upon survival within 5 years from diagnosis varied among regions relative to Toronto (e.g., RR Ottawa = 1.21, RR Hamilton = 1.20). CONCLUSIONS: There is regional variation in the utilization of resection with permanent colostomy, and in the utilization of postoperative RT among cases not undergoing permanent colostomy. Regions with higher initial rates of resection plus permanent colostomy continue to experience higher probability of permanent colostomy 5 years after diagnosis of rectal cancer. Higher initial rates of permanent colostomy may be malleable to interventions aimed at improving overall outcomes.

A population-based study of the use and outcome of radical radiotherapy for invasive bladder cancer.

PURPOSE: The objective of this study is to describe the use and outcome of radical radiotherapy for bladder cancer in the province of Ontario, Canada, between 1982 and 1994. METHODS: Electronic records of invasive bladder cancer (ICD code 188) from the Ontario Cancer Registry were linked to surgical records from all Ontario hospitals and radiotherapy (RT) records from all Ontario cancer centers. We identified cases receiving radical RT by selecting RT records containing "bladder" or "pelvis" anatomic region codes and a radical or curative intent code (or dose >39.5 Gy if intent missing). We identified cases receiving salvage total cystectomy by selecting total cystectomy procedure codes occurring at any time beyond 4 months from the start of radical RT. We used life table methods to compute the following: the time from diagnosis to radical RT, the time from radical RT to salvage cystectomy, overall and cause-specific survival from radical radiotherapy to death, and overall and cause-specific survival from salvage cystectomy to death. We modeled the factors associated with time to death, time to cystectomy conditional on survival, and time to cystectomy or death, whichever came first, using Cox proportional hazards regression. RESULTS: From the 20,906 new cases of bladder cancer diagnosed in Ontario from 1982 to 1994, we identified 1,372 cases treated by radical radiotherapy (78% male, 22% female; mean age 69.8 years). The median interval to start of radical RT from diagnosis was 13.4 weeks. Ninety-three percent of patients were treated on high-energy linacs, and the most common dose/fractionation scheme was 60 Gy/30 (31% of cases). Five-year survival rates were as follows: bladder cancer cause-specific, 41%; overall, 28%; cystectomy-free, 25%; bladder cancer cause-specific following salvage cystectomy, 36%; overall following salvage cystectomy, 28%. Factors associated with a higher risk of death and a poorer cystectomy-free survival were histology (squamous or nonpapillary transitional cell carcinoma [TCC]) and advanced age. CONCLUSION: This population-based study confirms previous institutional studies and clinical trials and shows that radical RT has a curative role in the management of invasive bladder cancer and allows about one-quarter of patients receiving radiotherapy to survive 5 years while retaining the bladder. Salvage cystectomy following RT provides a chance of cure at the time of bladder relapse.

Mortality from myocardial infarction following postlumpectomy radiotherapy for breast cancer: a population-based study in Ontario, Canada.

PURPOSE: To compare the risk of mortality from myocardial infarction (MI) after left-sided postlumpectomy radiotherapy (RT) to the risk after right-sided postlumpectomy RT. METHODS: We conducted a population-based cohort study of cases of invasive female breast cancer in Ontario, diagnosed between January 1, 1982 and December 31, 1987 (n = 25,570). Records of the Ontario Cancer Registry (OCR) were linked to hospital procedure and discharge abstracts and to RT records from Ontario cancer centers. A case was labelled as lumpectomy if this was the maximum breast surgery within 4 months of diagnosis. Postlumpectomy RT occurred up to 1 year postdiagnosis. Laterality was assigned from the laterality descriptor of the RT records. A case was labelled as having had a fatal MI if ICD code 410 (myocardial infarction) was recorded as the cause of death in the OCR. We used logistic regression to compare the likelihood of utilization of: 1. Dose per fraction > 2.00 Gy; 2. cobalt vs. linac; and 3. boost RT. We used life table analysis and the log rank test comparing the time to fatal MI from diagnosis of breast cancer between women who received left-sided postlumpectomy RT and women who received right-sided. We used Cox proportional hazards models to study the relative risk for left-sided cases overall, and stratified by age, RT characteristics, and among conditional survival cohorts. RESULTS: Postlumpectomy RT was received by 1,555 left-sided and 1,451 right-sided cases. With follow-up to December 31, 1995, 2% of women with left-sided RT had a fatal MI compared to 1% of women with right-sided RT. Comparison of the time to failure between women who had left-sided RT and women who had right-sided RT showed the left-sided RT group to be associated with a higher risk of fatal MI (p = 0.02). Adjusting for age at diagnosis, the relative risk for fatal MI with left-sided postlumpectomy RT was 2.10 (1.11, 3.95). CONCLUSION: Among women who received postlumpectomy RT for breast cancer in Ontario between 1982-1987, left-sided postlumpectomy RT was associated with a higher risk of fatal MI compared to right-sided.

A real-time audit of radiation therapy in a regional cancer center.

PURPOSE: To report the development, structure, and implementation of a real-time clinical radiotherapy audit of the practice of radiation oncology in a regional cancer center. METHODS AND MATERIALS: Radiotherapy treatment plans were audited by a real-time peer-review process over an 8-year period (1989-1996). The overall goal of the audit was to establish a process for quality assurance (QA) of radiotherapy planning and prescription for individual patients. A parallel process was developed to audit the implementation of intervention-specific radiotherapy treatment policies. RESULTS: A total of 3052 treatment plans were audited. Of these, 124 (4.1%) were not approved by the audit due to apparent errors in radiation planning. The majority of the nonapproved plans (79%) were modified prior to initiating treatment; the audit provided important clinical feedback about individual patient care in these instances. Most of the remaining nonapproved plans were deviations from normal practice due to patient-specific considerations. A further 110 (3.6% of all audited plans) were not approved by the audit due to deviations from radiotherapy treatment policy. A minority of these plans (22%) were modified prior to initiating treatment and the remainder provided important feedback for continuous quality improvement of treatment policies. CONCLUSION: A real-time audit of radiotherapy practice in a regional cancer center setting proved feasible and provided important direct and indirect patient benefits.

Mortality from myocardial infarction after adjuvant radiotherapy for breast cancer in the surveillance, epidemiology, and end-results cancer registries.

PURPOSE: To compare the risk for fatal myocardial infarction (MI) after adjuvant radiotherapy (RT) for left-sided breast cancer with the risk for MI after adjuvant RT for right-sided breast cancer. METHODS: We studied women with local- and regional-stage breast cancer diagnosed from 1973 to 1992 from the Surveillance, Epidemiology, and End-Results (SEER) cancer registries. We performed life-table analysis, the log-rank test, and Cox proportional hazards regression to compare the time to fatal MI from diagnosis between left-sided and right-sided cases, censoring deaths from other causes. RESULTS: Among irradiated patients, the relative risk (RR) for fatal MI in women with left-sided breast cancer was 1.17 (95% confidence interval [CI], 1.01 to 1.36), controlling for age, compared with those with right-sided breast cancer. The RR for fatal MI among left-sided cases was increased for those under the age of 60 years (RR = 1.98; 95% CI, 1.31 to 2.97) compared with right-sided cases, but not at age 60 years or older. Among women with irradiated regional-stage cancer who were younger than 60 years of age, the risk was significantly increased (RR = 2.24; 95% CI, 1.38 to 3.64) for those with left-sided compared with right-sided breast cancer, but not among patients aged 60 years or older. Among irradiated local-stage cases, the risk for those with left-sided breast cancer was not significantly elevated in either age category. Analysis of 5-year conditional survival cohorts showed an increased risk for irradiated left-sided cases among women younger than 60 years of age in the 10- to 15-year conditional survival cohort (RR = 5.28; 95% CI, 1.82 to 15.3). CONCLUSION: Adjuvant RT for left-sided breast cancer diagnosed in women younger than 60 years of age is associated with a higher risk for fatal MI 10 to 15 years later compared with adjuvant RT for right-sided cases.

Radiotherapy for breast cancer in Ontario: rate variation associated with region, age and income.

OBJECTIVE: To describe the variation in the use of radiotherapy (RT) in women in Ontario within 1 year of diagnosis of breast cancer, from 1982 to 1991, and to identify factors associated with these variations. DESIGN: Retrospective, population-based cohort study. SETTING: Ontario. POPULATION: All women registered by the Ontario Cancer Registry (OCR) with a diagnosis of invasive breast cancer between Jan. 1, 1982, and Dec. 31, 1991. INTERVENTIONS: RT to any anatomic site within 1 year of the diagnosis of breast cancer. OUTCOME MEASURES: Odds of receiving RT within 1 year of diagnosis (from RT files from all radiotherapy departments in Ontario) associated with year and with geographic, age-related and socioeconomic factors. RESULTS: Use of RT within 1 year of diagnosis increased from 21.1% (95% confidence interval [CI] 19.8-22.4) in 1982 to 44.7% (95% CI 43.4-46.0) in 1991 (p < 0.0001). Among the regions of Ontario, the use of RT varied from 24.5% (95% CI 23.5-25.6) to 44.4% (95% CI 43.0-45.9) (p < 0.0001). Increasing age was associated with decreasing likelihood of receiving RT (test for trend p < 0.0001), as was decreasing income (test for trend p < 0.0001). CONCLUSIONS: The use of RT within 1 year of the diagnosis of breast cancer in women in Ontario varies by region, age and income. Despite universal and comprehensive health insurance coverage, women with breast cancer in some populous regions of Ontario were less likely to receive RT within 1 year of their diagnosis than women in other populous regions.