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S W Duffy

Publications and source records attributed to S W Duffy.

At least 19 recordsLinked to original sources
PubMed2006

Family history and risk of lung cancer: age-at-diagnosis in cases and first-degree relatives.

To investigate the little known risk of lung cancer at an early age when a first-degree relative has had such a diagnosis, 579 incident cases and 1157 population controls were studied in Liverpool between 1998 and 2004 using standardised questionnaires covering demography and lifestyle. A history of lung cancer in first-degree relatives was associated with a significantly increased risk in the proband where in both individuals the cancers were diagnosed before the age of 60 years (odds ratio (OR)=4.89; 95% confidence interval (CI): 1.47-16.25). A significantly elevated risk of lung cancer was also observed in association with a relative affected before the age of 60 years, regardless of age-at-onset of the disease (OR=2.08; 95% CI: 1.20-3.59). This finding is strongly consistent with a genetic component in early-onset lung cancer risk.

Age of Onset↗
PubMed2006

Excess cases of prostate cancer and estimated overdiagnosis associated with PSA testing in East Anglia.

This study aimed to estimate the extent of 'overdiagnosis' of prostate cancer attributable to prostate-specific antigen (PSA) testing in the Cambridge area between 1996 and 2002. Overdiagnosis was defined conceptually as detection of prostate cancer through PSA testing that otherwise would not have been diagnosed within the patient's lifetime. Records of PSA tests in Addenbrookes Hospital were linked to prostate cancer registrations by NHS number. Differences in prostate cancer registration rates between those receiving and not receiving prediagnosis PSA tests were calculated. The proportion of men aged 40 years or over with a prediagnosis PSA test increased from 1.4 to 5.2% from 1996 to 2002. The rate of diagnosis of prostate cancer was 45% higher (rate ratios (RR)=1.45, 95% confidence intervals (CI) 1.02-2.07) in men with a history of prediagnosis PSA testing. Assuming average lead times of 5-10 years, 40-98% [corrected] of the PSA-detected cases were estimated to be overdiagnosed. In East Anglia, from 1996 to 2000, a 1.6% excess of cases was associated with PSA testing (around a quarter of the 5.3% excess incidence cases observed in East Anglia from 1996 to 2000). Further quantification of the overdiagnosis will result from continued surveillance and from linkage of incidence to testing in other hospitals.

Adult↗
PubMed2006

Screening younger women with a family history of breast cancer--does early detection improve outcome?

Women with a family history are often offered mammographic surveillance at an earlier age and with greater frequency than those in the National Breast Screening Programme. In this study, we compared the survival of 62 breast cancer patients diagnosed in the context of a family history clinic offering 12-18 monthly mammographic screening with that of 1108 patients of the same age range but having no exposure to screening. We subtracted the expected additional observation time due to lead time from the survival of the screen-detected cases. Survival was significantly better in the family history group with relative hazards of 0.19 (95% CI 0.07-0.52, P<0.001) for breast cancer death and 0.19 (95% CI 0.08-0.43, P<0.001) for disease-free survival. After correcting for lead-time, the relative hazards were 0.24 (95% CI 0.09-0.66, P=0.005) for breast cancer death and 0.25 (95% CI 0.11-0.57, P<0.001) for disease-free survival. These results strongly suggest that screening younger women with a family history of breast cancer leads to improved survival. More precise estimates of the benefit will accrue from further follow-up and other such studies.

Adult↗
PubMed2005

Audit of negative assessments in a breast-screening programme in women who later develop breast cancer-implications for survival.

The aim of this study was to examine observed short-term survival, to estimate future survival, and to assess the impact on survival of amending procedures to avoid false negatives in women recalled for further assessment due to a suspicious screening mammogram. From the start of screening in the seven centres in the East Anglian region, 1 April 1989 to 31 December 1999, 503493 women from a total population of 2.2 million were screened, 25346 were recalled for an assessment and 3689 were diagnosed with breast cancer. Of the 21657 women given a negative result at these assessments, 193 women were subsequently diagnosed with 194 breast tumours at the site previously assessed. These women were followed up for survival, with survival analysis adjusting for host and tumour attributes. We also predicted long-term survival using the pathological features of the tumours diagnosed. From previous estimates of tumour progression rates, we estimated the reduction in incidence of advanced tumours and the potential saving of lives had unsatisfactory assessments been carried out within guidelines. There were 17 deaths, 15 in women who had unsatisfactory assessments. Five-year survival was estimated at 93% (95% CI: 88-97%) for breast cancer and 91% (95% CI: 86-95%) for all cause deaths. Women with positive nodes and/or larger tumours had significantly worse survival. Twenty years survival for women with unsatisfactory assessments was estimated at 66% (35 deaths) and predicted a potential saving of 7-9 lives (14-18% reduction in expected fatality within this special tumour population) had original assessments been carried out within current guidelines. This retrospective audit of a small and special tumour population shows a potential reduction in breast cancer deaths of 18%, had current guidelines been available for the original assessments. Increased use of percutaneous biopsy in recent years should address the problem.

Breast Neoplasms↗
PubMed2005

What should the detection rates of cancers be in breast screening programmes?

Minimum detection rates at screening are sometimes laid down as standards for breast cancer screening programmes, based on underlying incidence of the disease in the age group screened. Detection rates should also depend on desired sensitivity, mean sojourn time, interscreening interval and the screening round--that is, prevalent (first) or incident (second or subsequent). In this paper, we use these quantities to derive expected, minimum and maximum detection rates proportional to the underlying incidence as well as estimated underlying incidence rates from extrapolation of prescreening trends in England and Wales to derive alternative standard minimum, expected and maximum detection rates per 1000 women screened for the UK Breast Screening Programme, as follows: minimum detection rates should be 4.1 and 4.3 at prevalence screen and incidence screens, respectively; expected rates should be 6.9 and 4.8 and maximum rates of 9.6 and 5.5. These are consistent with observed detection rates in the UK programme.

Breast Neoplasms↗
PubMed2004

Interaction of dense breast patterns with other breast cancer risk factors in a case-control study.

The question of interactions between breast density and other breast cancer risk factors is of interest, since it bears upon the use of density as a marker for changes in breast cancer risk. We studied breast parenchymal patterns and 13 other potential risk factors for breast cancer in 172 breast cancer cases and 338 age-matched controls in Singapore. Dense breast patterns were defined as having Tabar parenchymal pattern IV or V. We found significant interactions between dense patterns and ethnic group (P=0.046), and between dense patterns and number of deliveries (P=0.04). Among women with nondense breast patterns, the non-Chinese had lower risk than the Chinese with an odds ratio (OR) of 0.47 (95% CI 0.24, 0.88), whereas in those with dense patterns, the non-Chinese had considerably higher risks (OR=5.34, 95% CI 0.54, 52.51). Alternatively expressed, the increased risk with dense patterns was only observed in the non-Chinese (OR=13.99, 95% CI 1.33, 146.99). Among parous women, the protective effect of three or more deliveries was only observed in those with dense breast patterns (OR=0.21, 95% CI 0.06, 0.70). Suggestive but nonsignificant interactions with dense patterns were observed for ever having delivered, age at first delivery, breast feeding and body mass index. The results are consistent with dense breast patterns as a marker for hormonal modification of breast cancer risk.

Adolescent↗
PubMed2004

A simple model for potential use with a misclassified binary outcome in epidemiology.

STUDY OBJECTIVE: Error in determination of disease outcome occurs in epidemiology, but such error is not usually corrected for in statistical analysis. A method of correction of risk estimates for misclassification of a binary disease outcome is developed here. METHODS: The method is a simple, closed form correction to the logistic regression estimate. A closed form variance estimate is also developed. SETTING: The method is illustrated in two studies, a cross sectional survey of cervicitis in Iran in 1996-97, as determined by inflammation on cervical smear specimens, and a case-cohort study of benign proliferative epithelial disease of the breast, in Canada 1980-88. MAIN RESULTS: The method provides corrected odds ratio estimates and corrects the spurious precision conferred by misclassification. CONCLUSIONS: The method is easy to apply and potentially useful, although potential failures of the assumptions involved should be borne in mind. It is necessary to give careful consideration to the plausibility or otherwise of the assumptions in the context of the individual study. Correction for misclassification of disease outcome may become more common with the development of readily applicable methods.

Bias↗
PubMed2004

Overdiagnosis in screening: is the increase in breast cancer incidence rates a cause for concern?

OBJECTIVES: To estimate the degree of overdiagnosis of breast cancer in a mammographic screening programme. SETTING: A mammography service screening programme in Florence, Italy. METHODS: We studied the incidence of breast cancer in Florence between 1990 and 1999, following the introduction of screening in 1990. Incidence of breast cancer in this period was compared with incidence between 1985 and 1989, before the introduction of screening. It was necessary to estimate the number of cancers that would have arisen in the absence of screening, but after the end of followup (31 December 1999), so that these were not misclassified as overdiagnosed tumours. Around 60,000 women aged 50-69 were invited for screening during the period of study. RESULTS: There were 2780 breast cancers diagnosed during the period of study (2626 were invasive). There was no significant evidence of overdiagnosis of invasive cancers. When invasive and in situ cancers were considered together, around 5% of cases were overdiagnosed. CONCLUSIONS: There is a small amount of overdiagnosis of ductal carcinoma in situ in mammography screening; however, this should not deter women from being screened. Training and practice in mammographic screening should emphasise detection of small, invasive lesions. Research into the natural history and treatment of the disease should aim at minimising overtreatment of those in situ lesions that are less likely to progress to invasive disease.

Breast Neoplasms↗
PubMed2004

Number needed to screen: lives saved over 20 years of follow-up in mammographic screening.

OBJECTIVE: To estimate the number needed to screen with mammography to save one life, based on a stated amount of screening activity and long-term follow-up for breast cancer death. SETTING: A randomised controlled trial of mammographic screening for breast cancer, with 77,080 women invited to screening and 55,985 not invited. The invited group was offered screening for seven years. Follow-up continued for a total of just over 20 years. METHODS: Number needed to screen for seven years to save one life over 20 years was calculated by dividing the number screened (not the number invited) by the total number of lives saved. Similarly, we calculated the number of mammographic examinations required to save one life. RESULTS: We estimate that the number of women needed to screen for seven years to save one life over 20 years is 465 (95% CI 324-819). The number of mammographic examinations needed to save one life was 1499 (95% CI 1046-2642). CONCLUSIONS: The number needed to screen to save one life is smaller than has been reported in the past. Mammographic screening is effective in absolute terms as well as relative. Long-term follow-up allowed us to estimate the absolute benefit with greater accuracy.

Adult↗
PubMed2004

A case-control study to estimate the impact on breast cancer death of the breast screening programme in Wales.

OBJECTIVES: The aim of this study was to estimate the effect of service screening, as provided by the NHS breast screening programme, on breast cancer mortality in Wales. Furthermore, we wished to ascertain whether a reduction in breast cancer mortality consistent with that observed in the randomised screening trials was being achieved. SETTING: The NHS Breast Screening Programme in Wales, managed by Breast Test Wales, with headquarters in Cardiff. METHODS: A case-control study design with 1:2 matching. The cases were deaths from breast cancer in women aged 50-75 years at diagnosis who were diagnosed after the instigation of screening in 1991 and who died after 1998. The controls were women who had not died of breast cancer or any other condition during the study period. One was from the same GP practice and the other from a different GP practice within the same district, matched by year of birth. RESULTS: Based on 419 cases, the odds ratio for risk of death from breast cancer for women who have attended at least one routine screen compared to those never screened was 0.62 (95% confidence interval [CI] 0.47-0.82, p=0.001). After excluding cases diagnosed prior to 1995 and adjusting for self-selection bias, the estimated mortality reduction was 25% (odds ratio=0.75, 95% CI 0.49-1.14, p=0.09). CONCLUSION: The Breast Test Wales screening programme is achieving a reduction in breast cancer mortality of 25% in women attending for screening, which is consistent with the results of the randomized controlled trials of mammographic screening.

Aged↗
PubMed2004

Mammographic casting-type calcification associated with small screen-detected invasive breast cancers: is this a reliable prognostic indicator?

AIM: The aim of the present study was to establish whether mammographic casting-type calcification associated with small screen-detected invasive breast cancers is a reliable prognostic indicator. METHODS AND MATERIALS: We retrospectively identified 50 consecutive women diagnosed with an invasive cancer less than 15 mm who showed associated casting calcification on their screening mammograms. Controls were identified that showed no microcalcification and were matched for tumour size, histological type and lymph node status. A minimum of 5 years follow-up was obtained, noting recurrence and outcome. Conditional and unconditional logistic regression, depending on the outcome variable, were used to analyse the data, taking the matched design into account in both cases. Where small numbers prohibited the use of logistic regression, Fisher's exact test was used. RESULTS: Five deaths from breast cancer occurred out of the 50 cases, of which three were lymph node positive, two were lymph node negative and none were grade 3. None of the 78 control cases died from breast cancer. The difference in breast cancer death rates was significant by Fisher's exact test (p=0.02). Risk of recurrence was also significantly increased in the casting cases (OR=3.55, 95% CI 1.02-12.33, p=0.046). CONCLUSION: Although the overall outcome for small screen-detected breast cancers is good, our study suggests that casting calcification is a poorer prognostic factor. The advantage of a mammographic feature as an independent prognostic indicator lies in early identification of high-risk patients, allowing optimization of management.

Breast Neoplasms↗
PubMed2003

Socioeconomic effects on breast cancer survival: proportion attributable to stage and morphology.

Breast cancer patients of lower socioeconomic status tend to have poorer survival. Among 10 865 cases of breast cancer from the East Anglian Cancer Registry diagnosed between 1982 and 1993, we estimated the extent to which the differences in survival by socioeconomic status, measured by both occupational and area-based methods, can be explained by differences between socioeconomic groups in stage and morphological type of tumour. In univariate survival analyses, lower social class (manual occupation) was associated with a relative hazard of 1.32 (95% CI 1.12-1.55) for death from breast cancer as underlying cause. Women resident in the most deprived area had a relative hazard of 1.21 (0.95-1.54) for death from breast cancer as underlying cause. Stage of disease accounted for 28% of the effect of social class on survival but for none of the effect of deprivation category. Morphological type accounted for 3% of the effect of social class and none of the effect of deprivation category. Thus, stage at presentation explains some but not all of the socioeconomic differences in breast cancer survival. Future research on histological grade and socioeconomic status is indicated.

Breast Neoplasms↗
PubMed2003

The relative contributions of screen-detected in situ and invasive breast carcinomas in reducing mortality from the disease.

We aimed to quantify the benefits of detecting ductal carcinoma in situ (DCIS) and of downwards stage-shifting within invasive tumours in mammographic screening. Using data from the Swedish Two-County Trial of breast cancer screening, we examined the 20-year death rates from invasive tumours of stage II or worse, invasive tumours of stage I and DCIS. We then used these rates and their respective incidences in invited (active study population, ASP) and control (passive study population, PSP) arms of the trial, to estimate the numbers of deaths avoided by downward stage-shifting the larger stage II or worse tumours to stage I and the stage I cancers to DCIS. We also studied the association between the mortality reduction achieved and the proportion of DCIS cases detected in the randomised trials of breast cancer screening. In the Swedish Two County Trial, 141 breast cancer deaths were avoided in the ASP compared with the PSP at approximately 20 years of follow-up. Of these, 65% (91/141) were avoided as a result of stage-shifting from invasive stage II or worse to invasive stage I, and 5% (7/141) as a result of stage-shifting from invasive stage I to DCIS. If we assumed that 10% of stage II or worse tumours avoided were shifted not to stage I, but to DCIS, the estimated number of deaths prevented by shifting from invasive disease to in situ was 17, which is 12% of all deaths prevented. When the results of all the randomised trials of breast cancer screening were reviewed, there was no clear association between the percentage of DCIS cases diagnosed and the observed mortality reduction. We conclude that compared with downward stage-shifting of invasive tumours, detection of DCIS plays a small part in saving lives from breast cancer. Treatment decisions in DCIS, as in invasive carcinoma, should take full account of histopathological, clinical and radiological attributes of the tumour.

Adult↗
PubMed2003

Quantifying the potential problem of overdiagnosis of ductal carcinoma in situ in breast cancer screening.

The relevance of detection of ductal carcinoma in situ (DCIS) in a breast cancer screening programme, and the extent of overdiagnosis of non-progressive lesions, remains controversial. It was the purpose of this paper to estimate the incidence of non-progressive, 'overdiagnosed' DCIS. We defined non-progressive DCIS (DCIS(0)) as DCIS which could not have progressed to invasive disease if left untreated. Progressive DCIS (DCIS(1)) was defined as DCIS which has the propensity to progress to invasive disease. We fitted a Markov process model of the incidence of progressive and non-progressive DCIS, the transition of the former to preclinical invasive disease and the subsequent progression to clinical symptomatic cancer. We used data from the Swedish Two-County Trial and from service screening programmes in the UK, Netherlands, Australia and the USA to estimate the incidence of progressive and non-progressive DCIS, and the detection rates of each at the first and subsequent screening. Average incidence of non-progressive DCIS was 1.11 per 100000 per year. Average incidence of progressive DCIS was 2.1 per 1000 per year. At prevalence screen, 37% of DCIS cases were estimated to be non-progressive. A woman attending prevalence screen has a 19 times greater chance of having a progressive DCIS or an invasive tumour diagnosed than of having a non-progressive DCIS diagnosed. At incidence screen, only 4% of DCIS cases were estimated to be non-progressive. A woman attending an incidence screen has a 166 times higher probability of having a progressive DCIS or invasive lesion diagnosed than of having a non-progressive DCIS diagnosed. There is an element of overdiagnosis of DCIS in breast cancer screening, but the phenomenon is small in both relative and absolute terms.

Adult↗
PubMed2003

Breast density and breast cancer risk factors in a high-risk population.

This study investigates relationships between familial and hormonal risk factors and breast density in women at high risk of developing breast cancer. The subjects are a subset of 102 women from the international breast cancer intervention study (IBIS), for whom a series of repeated measurements of breast density were available. Details of familial and hormonal risk factors for breast cancer were collected at entry and multivariate ordered logistic regression used to identify risk factors for increased breast density. Lower body mass index and nulliparity were associated with high breast density, whereas smoking was associated with lower breast density. It is not yet known whether a reduction in breast density will lead to a corresponding reduction in breast cancer risk, so we propose that changes in breast density be investigated as a potential early indicator of efficacy in chemoprevention trials for breast cancer.

Body Mass Index↗