PubMed Health⌕ Search

Biomedical subjects

C J Baines

Publications and source records attributed to C J Baines.

At least 19 recordsLinked to original sources
PubMed1992

Canadian National Breast Screening Study: 1. Breast cancer detection and death rates among women aged 40 to 49 years.

OBJECTIVES: To evaluate the efficacy of the combination of annual screening with mammography, physical examination of the breasts and the teaching of breast self-examination in reducing the rate of death from breast cancer among women aged 40 to 49 years on entry. DESIGN: Individually randomized controlled trial. SETTING: Fifteen urban centres in Canada with expertise in the diagnosis and treatment of breast cancer. PARTICIPANTS: Women with no history of breast cancer and no mammography in the previous 12 months were randomly assigned to undergo either annual mammography and physical examination (MP group) or usual care after an initial physical examination (UC group). The 50,430 women enrolled from January 1980 through March 1985 were followed for a mean of 8.5 years. DATA COLLECTION: Derived from the participants by initial and annual self-administered questionnaires, from the screening examinations, from the patients' physicians, from the provincial cancer registries and by record linkage to the Canadian National Mortality Data Base. Expert panels evaluated histologic and death data. MAIN OUTCOME MEASURES: Rates of referral from screening, rates of detection of breast cancer from screening and from community care, nodal status, tumour size, and rates of death from all causes and from breast cancer. RESULTS: Over 90% of the women in each group attended the screening sessions or returned the annual questionnaires, or both, over years 2 to 5. The characteristics of the women in the two groups were similar. Compared with the Canadian population, the participants were more likely to be married, have fewer children, have more education, be in a professional occupation, smoke less and have been born in North America. The rate of screen-detected breast cancer on first examination was 3.89 per 1000 in the MP group and 2.46 per 1000 in the UC group; more node-positive tumours were found in the MP group than in the UC group. During years 2 through 5 the ratios of observed to expected cases of invasive breast cancer were 1.26 in the MP group and 1.02 in the UC group. Of the women with invasive breast cancer through to 7 years, 191 and 157 women in the MP and UC groups respectively had no node involvement, 55 and 43 had one to three nodes involved, 47 and 23 had four or more nodes involved, and 38 and 49 had an unknown nodal status. There were 38 deaths from breast cancer in the MP group and 28 in the UC group. The ratio of the proportions of death from breast cancer in the MP group compared with those in the UC group was 1.36 (95% confidence interval 0.84 to 2.21). The survival rates were similar in the two groups. The highest survival rate occurred among women whose cancer had been detected by mammography alone. CONCLUSION: The study was internally valid, and there was no evidence of randomization bias. Screening with yearly mammography and physical examination of the breasts detected considerably more node-negative, small tumours than usual care, but it had no impact on the rate of death from breast cancer up to 7 years' follow-up from entry.

Adult↗
PubMed1992

Canadian National Breast Screening Study: 2. Breast cancer detection and death rates among women aged 50 to 59 years.

OBJECTIVE: To evaluate the efficacy of annual mammography over and above annual physical examination of the breasts and the teaching of breast self-examination among women aged 50 to 59 on entry. DESIGN: Individually randomized controlled trial. SETTING: Fifteen urban centres in Canada with expertise in the diagnosis and treatment of breast cancer. PARTICIPANTS: Women with no history of breast cancer and no mammography in the previous 12 months were randomly assigned to undergo either annual mammography and physical examination (MP group) or annual physical examination only (PO group). The 39,405 women enrolled from January 1980 through March 1985 were followed for a mean of 8.3 years. DATA COLLECTION: Derived from the participants by initial and annual self-administered questionnaires, from the screening examinations, from the patients' physicians, from the provincial cancer registries and by record linkage to the Canadian National Mortality Data Base. Expert panels evaluated histologic and death data. MAIN OUTCOME MEASURES: Rates of referral from screening, rates of detection of breast cancer from screening and from community care, nodal status, tumour size and rates of death from all causes and from breast cancer. RESULTS: Over 85% of the women in each group attended the screening sessions after screen 1. The characteristics of the women in the two groups were similar. Compared with the Canadian population the participants were more likely to be married, have fewer children, have more education, be in a professional occupation, smoke less and have been born in North America. The rate of screen-detected breast cancer on first examination was 7.20 per 1000 in the MP group and 3.45 per 1000 in the PO group, more node-positive tumours were found in the MP group than in the PO group. At subsequent screens the detection rates were a little less than half the rates at screen 1. During years 2 through 5 the ratios of observed to expected cases of invasive breast cancer were 1.28 in the MP group and 1.18 in the PO group. Of the women with invasive breast cancer through to 7 years, 217 in the MP group and 184 in the PO group had no node involvement, 66 and 56 had one to three nodes involved, 32 and 34 had four or more nodes involved, and 55 and 46 had an unknown nodal status. There were 38 deaths from breast cancer in the MP group and 39 in the PO group. The ratio of the proportions of death from breast cancer in the MP group compared with those in the UC group was 0.97 (95% confidence interval 0.62 to 1.52). The survival rates were similar in the two groups. Women whose cancer had been detected by mammography alone had the highest survival rate. CONCLUSION: The study was internally valid, and there was no evidence of randomization bias. Screening with yearly mammography in addition to physical examination of the breasts detected considerably more node-negative, small tumours than screening with physical examination alone, but it had no impact on the rate of death from breast cancer up to 7 years' follow-up from entry.

Breast Neoplasms↗
PubMed1992

Breast self-examination.

A review of publications on breast self-examination (BSE) up to the middle of 1991 showed that evidence supporting BSE has strengthened since 1989. BSE is associated with a smaller size of tumor at diagnosis and has the potential to reduce breast cancer mortality. Mortality reduction is likely to be achieved only if BSE is competently performed and if appropriate diagnostic follow-up is accessible. Because screening is justified when preclinical disease is prevalent, BSE practice is important for women 40 years of age and older.

Breast Neoplasms↗
PubMed1992

Physical examination of the breasts in screening for breast cancer.

No currently available evidence from breast cancer screening studies provides strong justification for the implementation of screening in elderly females. Because it is an absence of evidence rather than negative evidence which pertains, it is concluded that if screening is introduced it should include both mammography and clinical examination of the breasts because the two complement one another. As well, stringent quality control procedures are required for both modalities. It is possible that clinical examination of the breasts performed by a nurse-examiner will enhance compliance with screening schedules.

Adult↗
PubMed1990

Changes in breast self-examination behavior achieved by 89,835 participants in the Canadian National Breast Screening Study.

Breast self-examination (BSE) behavior was analyzed in 89,835 participants in the National Breast Screening Study (NBSS) of whom 64,619 were eligible for annual rescreening and 25,216 were followed by mail after a single screen exam. Among those eligible for rescreening, BSE competence scores based on seven BSE criteria significantly improved over time and correlated directly with reported BSE frequencies. Among all participants, the proportion reporting BSE frequencies of greater than or equal to 12/year increased over time from approximately 20% on entry to 50% to 64% at final screen. Similarly, reports of zero frequency diminished from 50% to 10% to 15%. Variables such as educational status, age (fifth versus sixth decades), eligibility for mammography, smoking history, and ethnic origin had negligible or no influence on BSE competence. However, women with first-degree relatives with breast cancer had significantly higher BSE scores. NBSS experience suggests that most women who enter screening programs will upgrade their BSE skills if subjected to brief episodes of repeated BSE instruction.

Adult↗
PubMed1990

Women's attitudes to screening after participation in the National Breast Screening Study. A questionnaire survey.

A self-administered questionnaire study exploring women's attitudes to breast screening after participation in the Canadian National Breast Screening Study (NBSS) achieved an 82% response rate. Of active respondents (AR) attending two to five screening examinations, 1582 had received annual mammography (MA) and physical examination (PE) of the breasts and 548 received annual PE alone. Of 139 dropouts after the first screening, 105 received MA and PE and 34 received PE alone. Dropout respondents (DR) were significantly less likely than AR to report receiving very prompt (46% versus 66%), very courteous (73% versus 92%), or very competent examinations (74% versus 95%). Although 35% of those allocated to PE expressed disappointment with PE allocation compared with 9% of those allocated to MA, fewer of those allocated PE were prepared to accept MA in the future than those allocated MA (59% versus 73%). Of those who had MA, 36% reported moderate and 9% extreme discomfort from mammography. Almost half of each subgroup--MA allocations, PE allocations, and DR--preferred mammography every 2 to 3 years and 30% preferred mammography restricted to diagnostic purposes. Only 5% of AR reported anxiety after screening. National Breast Screening Study participation was a positive experience for 93%. An intention to do breast self-examination (BSE) was reported by 89% of AR and 79% of DR. Forgetfulness was a major impediment to BSE. Disincentives for screening were excessive distance to center, painful mammography, fear of radiation, lack of time, and preference for own physician. Convenient location, punctual appointments, and courteous and supportive staff should enhance screening compliance.

Adult↗
PubMed1990

The role of the reference radiologist. Estimates of inter-observer agreement and potential delay in cancer detection in the national breast screening study.

The Canadian National Breast Screening Study (NBSS) is a randomized controlled trial to assess the effect of screening on breast cancer mortality. The NBSS designated a single reference radiologist who blindly reviewed over the course of the study 5200 randomly selected two-view mammographic examinations of women not known to have breast cancer. He also reviewed 575 screening-detected breast cancer (SBC) cases and 102 interval breast cancer (IBC) cases. All cancers were histologically proven. As a result of the reviews, comments on inter-observer agreement, interpretation, and technical quality were conveyed on an ongoing basis to radiologists appointed to 15 NBSS screening centers. Agreement of the reference radiologist with center radiologists was better for breast cancer cases (kappa = 0.511, P less than .002) than for those not known to have breast cancer (kappa = 0.307, P less than .002). Observer error and technical problems led to delayed detection in 22% of SBCs and 35% of IBCs. Another 11% of SBCs and 58% of IBCs were probably mammographically occult. No similarly comprehensive review of mammography during a screening program has been published. Suggestions arising from the NBSS review were sometimes resisted by center radiologists. Measures are suggested which might facilitate acceptance of recommendations arising from audit mechanisms in mammography screening programs, thereby enhancing opportunities for mammographic excellence.

Breast Neoplasms↗
PubMed1990

Canadian National Breast Screening Study: assessment of technical quality by external review.

Mammograms from the Canadian National Breast Screening Study (NBSS) were reviewed by three external experts to provide an objective evaluation of their technical quality, to establish a model for auditing mammograms in a screening program, and to assess whether NBSS mammograms improved over time. The sample reviewed included 10 randomly chosen mammograms from each of 15 screening centers for each calendar year of their operation between 1980 and 1987. All 830 mammograms were reviewed on two consecutive days in randomized sequence by each reader, and rated 0-3 for each of four criteria including positioning and image quality, with a total possible score of 0-12. Although the mammograms were not in temporal sequence when reviewed, the scores assigned by each reader were significantly higher for mammograms dating from later years. Subjects' ages at entry (40-49 vs 50-59 years) did not affect the score. The largest increase in scores was associated with a 1985 protocol change in which mediolateral oblique positioning replaced straight mediolateral positioning. This study reinforces the importance of monitoring technical quality in screening programs and establishes that the NBSS benefited from technical improvements during its operation. A retrospective review of NBSS mammography by three external reviewers confirmed that technical quality improved from 1980 to 1987. This improvement was associated with improved technology (film, processing, and units) and with the quality assurance programs operating during the NBSS, which identified problems and offered remedies.

Adult↗
PubMed1989

Physical examination. Its role as a single screening modality in the Canadian National Breast Screening Study.

Although often recommended as an important component in screening for breast cancer, physical examination of the breasts (PE) by medical professionals has not been well evaluated. The Canadian National Breast Screening Study (NBSS) permits estimation of sensitivity, specificity, and positive predictive value (PPV) of PE alone as performed by screen-examiners because 50% of the 89,835 NBSS participants did not receive mammography. There were 19,965 women aged from 50 to 59 years who were eligible to receive four or five annual PEs from 77 nurse-examiners, in 12 screen centers outside Quebec province and 58 physician-examiners in three screen centers in Quebec. The gold standard was histologically proven breast cancer. When a test was positive the participant was referred to the study surgeon for review. For screens one to five, sensitivity was 83, 71, 57, 83, and 77; specificity was 88, 94, 96, 96, and 96; and PPV was 3, 3, 4, 3, and 4, respectively. For 25,620 women aged 40 to 49 years who were eligible to receive only one PE, sensitivity was 71, specificity 84, and PPV 1.5. Using a binomial regression model, X2 for heterogeneity suggested there was no difference between nurse and physician examiners (P = 0.6879). Similar estimates made for the surgeons who performed 8914 reviews showed that sensitivity and PPV were higher than for the screen examiners and specificity was lower. These results support the conclusion that physical examination of the breasts by trained nurses is a useful component in screening for breast cancer.

Adult↗
PubMed1989

Cigarette smoking and breast cancer: case-control studies of prevalent and incident cancer in the Canadian National Breast Screening Study.

Two case-control studies of Canadian women aged 40-59 years are reported investigating the relation of cigarette smoking with initial visit (prevalent) and subsequent visit (incident) breast cancer detection, respectively, within the Canadian National Breast Screening Study. The analysis of prevalent breast cancer (1982-1985), which involved 254 cases and 762 controls, showed no evidence of an elevated risk for women with a history of cigarette smoking, with odds ratios of 0.9 (95% confidence interval (Cl) 0.6-1.5) and 1.2 (95% Cl 0.8-1.8) in premenopausal and postmenopausal subjects, respectively. Similarly, in the incident breast cancer analysis (1981-1987) based on 317 cases and 951 controls, women with a history of cigarette smoking had odds ratios of 1.2 (95% Cl 0.8-2.0) and 1.2 (95% Cl 0.9-1.7) in the premenopausal and postmenopausal categories, respectively. No evidence of dose response or of elevated risk in ex-smokers or current smokers was found in either study. These results persisted despite adjustment for several important variables. The present data demonstrate no association between smoking and prevalent or incident breast cancer in either menopausal category, contradicting the authors' previous finding of a positive association with premenopausal prevalent disease earlier in this screening study. The relation of smoking and breast cancer remains controversial. Further study is required to determine whether an association truly does not exist or whether smoking might have both protective and harmful effects that are mediated through different pathways, thus accounting for the paradoxical findings in the literature to date.

Adult↗
PubMed1988

Sensitivity and specificity of first screen mammography in 15 NBSS centres.

We report the sensitivity and specificity of first screen mammography in a 15-centre randomized screening trial. Of 44,718 women who received mammography and physical examination at first screening, 238 were diagnosed with breast cancer at first screen, 34 in the 12-month interval after the first screen, and 98 at the second screen. Seventeen of the interval cases and 47 of the second-year cancers were defined as potentially detectable at first screening. Interpretations of first screen mammograms by radiologists at the screening centres were matched to known histological outcomes. Simultaneous blind review of 2908 cases, which included all cancers detected at first and second screenings as well as interval cancers, was done by a single reference radiologist. The sensitivity of the technique as carried out at all NBSS centres was 0.75, the specificity 0.94, the positive predictive value 0.07, and the negative predictive value 0.998.

Breast Neoplasms↗
PubMed1988

Incentives for breast self-examination: role of the calendar.

Calendars are generally believed to be useful in promoting compliance with breast self-examination (BSE). To test this belief, calendars were distributed to 1,166 women in the Canadian National Breast Screening Study for comparison with 1,027 other participants who received no calendar. Recipients were asked to note their BSE findings each month on the calendar and to return calendars at the next annual screen. Self-reported BSE frequencies and BSE competence scores revealed no significant difference between the recipients and nonrecipients at three points in time: one year prior to, at time of, and one year after calendar distribution. Only 136 women returned calendars as requested. Their improvement in the test period did not differ significantly from that shown by the control group or the nonreturners. Calendars do not seem to be useful in a population receiving annual screening and BSE instruction.

Adult↗