Trends in breast cancer during three decades in Denmark: stage at diagnosis, surgical management and survival

Risk of primary gastrointestinal cancers following incident non-metastatic breast cancer: a Danish population-based cohort study

Objective

We examined the risk of primary gastrointestinal cancers in women with breast cancer and compared this risk with that of the general population.

Design

Using population-based Danish registries, we conducted a cohort study of women with incident non-metastatic breast cancer (1990–2017). We computed cumulative cancer incidences and standardised incidence ratios (SIRs).

Results

Among 84 972 patients with breast cancer, we observed 2340 gastrointestinal cancers. After 20 years of follow-up, the cumulative incidence of gastrointestinal cancers was 4%, driven mainly by colon cancers. Only risk of stomach cancer was continually increased beyond 1 year following breast cancer. The SIR for colon cancer was neutral during 2–5 years of follow-up and approximately 1.2-fold increased thereafter. For cancer of the oesophagus, the SIR was increased only during 6–10 years. There was a weak association with pancreas cancer beyond 10 years. Between 1990–2006 and 2007–2017, the 1–10 years SIR estimate decreased and reached unity for upper gastrointestinal cancers (oesophagus, stomach, and small intestine). For lower gastrointestinal cancers (colon, rectum, and anal canal), the SIR estimate was increased only after 2007. No temporal effects were observed for the remaining gastrointestinal cancers. Treatment effects were negligible.

Conclusion

Breast cancer survivors were at increased risk of oesophagus and stomach cancer, but only before 2007. The risk of colon cancer was increased, but only after 2007.

Risk of primary urological and genital cancers following incident breast cancer: a Danish population-based cohort study

PURPOSE

The prevalence of breast cancer survivors has increased due to dissemination of population-based mammographic screening and improved treatments. Recent changes in anti-hormonal therapies for breast cancer may have modified the risks of subsequent urological and genital cancers. We examine the risk of subsequent primary urological and genital cancers in patients with incident breast cancer compared with risks in the general population.

METHODS

Using population-based Danish medical registries, we identified a cohort of women with primary breast cancer (1990-2017). We followed them from one year after their breast cancer diagnosis until any subsequent urological or genital cancer diagnosis. We computed incidence rates and standardized incidence ratios (SIRs) with 95% confidence intervals (CIs) as the observed number of cancers relative to the expected number based on national incidence rates (by sex, age, and calendar year).

RESULTS

Among 84,972 patients with breast cancer (median age 61 years), we observed 623 urological cancers and 1397 genital cancers during a median follow-up of 7.4 years. The incidence rate per 100,000 person-years was stable during follow-up (83 for urological cancers and 176 for genital cancers). The SIR was increased for ovarian cancer (1.37, 95% CI 1.23-1.52) and uterine cancer (1.37, 95% CI 1.25-1.50), but only during the pre-aromatase inhibitor era (before 2007). Moreover, the SIR of kidney cancer was increased (1.52, 95% CI 1.15-1.97), but only during 2007-2017. The SIR for urinary bladder cancer was marginally increased (1.15, 95% CI 1.04-1.28) with no temporal effects. No associations were observed for cervical cancer.

CONCLUSION

Breast cancer survivors had higher risks of uterine and ovarian cancer than expected, but only before 2007, and of kidney cancer, but only after 2007. The risk of urinary bladder cancer was moderately increased without temporal effects, and we observed no association with cervical cancer.

The impact of a breast cancer diagnosis on health-related quality of life. A prospective comparison among middle-aged to elderly women with and without breast cancer

Background The improved survival after breast cancer has prompted knowledge on the effect of a breast cancer diagnosis on health-related quality of life (HQoL). This study compared changes in HQoL among women from before to after breast cancer diagnosis with longitudinal changes among women who remained breast cancer-free. Material and methods The Danish Diet, Cancer and Health study included 57 053 cancer-free persons aged 50-64 years at baseline (1993-1997). We used data from first follow-up (1999-2002) and second follow-up (2010-2012) on HQoL [Medical Outcomes Survey, short form (SF-36)] obtained from 542 women aged 64-82 years with primary breast cancer (stages I-III) and a randomly matched sample of 729 women who remained breast cancer-free. Linear regression models were used to estimate the differences in changes in HQoL between women with and without breast cancer; the analyses were repeated with stratification according to age, comorbidity, partner support and time since diagnosis. Results Women with breast cancer reported significantly larger decreases in HQoL from before to after diagnosis than those who remained breast cancer-free (physical component summary, -2.0; 95% CI -2.8; -1.2, mental component summary, -1.5, 95% CI -2.3; -0.6). This association was significantly modified by comorbidity and time since diagnosis. Conclusions Women with breast cancer reported significantly larger HQoL declines than breast cancer-free women. Breast cancer diagnosis seems to have the greatest impact on HQoL closest to diagnosis and in women with comorbidity indicating that this group should be offered timely and appropriate follow-up care to prevent HQoL declines.

Explaining the Better Prognosis of Screening-Exposed Breast Cancers: Influence of Tumor Characteristics and Treatment

BACKGROUND

In England, population mammographic screening has been offered to women for over 20 years. Overall decrease in breast cancer mortality rates and improvements in cancer awareness and organization of medical care over this period call for a more current evaluation of the mediators behind the better prognosis of screening-exposed breast cancers.

METHODS

A case-control study was conducted within the English National Breast Screening Program. Women who died from primary breast cancer in 2008 to 2009 were matched (by year of birth, screening invitation, and area) to controls that received a diagnosis of invasive breast cancer at the time of the case diagnosis but survived the case death. Data were analyzed by unconditional logistic regression with adjustment for matching factors.

RESULTS

The unadjusted OR for dying from breast cancer associated with ever having attended breast screening was 0.44 [95% confidence interval (CI), 0.33-0.58]. After adjustment for lead time, overdiagnosis, and self-selection, the OR increased to 0.69 (95% CI, 0.50-0.94). Adjusting for tumor size, lymph node status, stage, grade, histopathology, and laterality accounted for all the screening effect (OR, 1.00; 95% CI, 0.71-1.40). Further adjustment for treatment factors only had a minimal impact on the OR (OR, 1.02; 95% CI, 0.72-1.45).

CONCLUSIONS

Our results suggest that earlier diagnosis, as reflected by tumor characteristics, remains the major mediator of the improvement in breast cancer survival due to participation in mammographic screening.

IMPACT

Mammographic screening continues to prevent breast cancer-related deaths in the epoch of adjuvant systemic therapy.

Breast cancer survival and stage at diagnosis in Australia, Canada, Denmark, Norway, Sweden and the UK, 2000-2007: a population-based study

BACKGROUND

We investigate whether differences in breast cancer survival in six high-income countries can be explained by differences in stage at diagnosis using routine data from population-based cancer registries.

METHODS

We analysed the data on 257,362 women diagnosed with breast cancer during 2000-7 and registered in 13 population-based cancer registries in Australia, Canada, Denmark, Norway, Sweden and the UK. Flexible parametric hazard models were used to estimate net survival and the excess hazard of dying from breast cancer up to 3 years after diagnosis.

RESULTS

Age-standardised 3-year net survival was 87-89% in the UK and Denmark, and 91-94% in the other four countries. Stage at diagnosis was relatively advanced in Denmark: only 30% of women had Tumour, Nodes, Metastasis (TNM) stage I disease, compared with 42-45% elsewhere. Women in the UK had low survival for TNM stage III-IV disease compared with other countries.

CONCLUSION

International differences in breast cancer survival are partly explained by differences in stage at diagnosis, and partly by differences in stage-specific survival. Low overall survival arises if the stage distribution is adverse (e.g. Denmark) but stage-specific survival is normal; or if the stage distribution is typical but stage-specific survival is low (e.g. UK). International differences in staging diagnostics and stage-specific cancer therapies should be investigated.

Breast cancer screening: review of benefits and harms, and recommendations for developing and low-income countries

Breast cancer is the most common cancer in women worldwide. The disease remains a public health concern as recent evidence indicates that the breast cancer burden has increased mainly in developing and low-income countries (DLICs). Despite the demonstrated benefits, the debate about the real benefits and harms of breast cancer screening is ongoing. Many experts believe that the benefits of screening, in terms of reduced breast cancer mortality, outweigh the harms, whereas others think the opposite. In this review, we assess the clinical utility of available screening modalities, present evidence, overdiagnosis, cost-effectiveness, and other pertinent issues. We also examine relevant data from DLICs to underscore the barriers and challenges that impede implementation of screening strategies in those populations. We also provide recommendations concerning rational preventive strategies for breast cancer control for women in DLICs.

Changes in body mass index and alcohol and tobacco consumption among breast cancer survivors and cancer-free women: a prospective study in the Danish Diet, Cancer and Health Cohort

BACKGROUND

A breast cancer diagnosis has been suggested as a teachable moment when a woman is more open to making healthier lifestyle changes. Little is known about the health behaviour changes women with breast cancer initiate compared to those made by other women.

MATERIAL AND METHODS

We examined changes in body mass index (BMI) and tobacco and alcohol consumption among women with a diagnosis of breast cancer and among cancer-free women. We used data from 23 420 women aged 50-64 years who participated in the Diet, Cancer and Health cohort, of whom 449 were diagnosed with breast cancer between baseline (1993-1997) and follow-up (2000-2002), and 22 971 remained cancer-free. We used multiple linear regression analysis to examine differences in BMI and alcohol and tobacco consumption between the two groups and to examine whether demographic and prognostic factors were associated with behavioural changes in women with breast cancer.

RESULTS

There were no significant differences in changes in BMI, alcohol and tobacco consumption between the two groups. Only in sub-analyses among women who lost weight between baseline and follow-up, women with breast cancer lost more weight than cancer-free women (β = 0.2; CI 0.1; 0.4), but residual confounding from stage cannot be excluded. Among the women with breast cancer we found no significant changes in BMI, alcohol and tobacco consumption by level of education, marital status, chemotherapy, hormone therapy or radiation.

CONCLUSION

Women with breast cancer did not reduce their BMI, or modify their alcohol use or tobacco consumption compared with cancer-free women. This study indicates that guidelines and interventions to change health behaviour are needed after a cancer diagnosis.

Unfavourable pattern of metastases in M0 breast cancer patients during 1978-2008: a population-based analysis of the Munich Cancer Registry

Little is known about time trends in metastases in the patients treated in routine health care facilities without metastases at diagnosis (M0) and about survival after these metastases. Data on 33,771 M0 patients with primary breast cancer diagnosed between 1978 and 2003 were obtained from the Munich Cancer Registry. Survival analyses were restricted to the patients with metastases within 5 years of the initial diagnosis. The incident number of the patients approximately doubled each period and 5-year overall survival increased from 77% in the first to 82% percent in the last period. 5490 (16%) M0 patients developed metastases within 5 years after the initial diagnosis. The hazard of developing metastases was lowest in the most recent period compared to the first period (HR = 0.50, P < 0.001). The hazard of dying after metastases was equal for patients diagnosed between 1978-1984 and 1995-2003 (HR 1.08, P = 0.3). The percentage of the patients that developed bone metastases decreased each time period, but the percentage primary liver and CNS metastases increased. Exclusion of site of metastases in the multivariate analysis led to a 20% (P = 0.02) higher hazard of dying following metastases in the last versus the first period. In the period 1978-2008, unfavourable changes in the pattern of metastases were exhibited and no improvement was observed in survival of the patients after occurrence of metastases. An explanation might be the increased use of adjuvant systemic treatment, which has less effect on the highly lethal liver and CNS metastases than on bone metastases. The increased use also appeared to contribute to the overall prevention of metastases in breast cancer and therefore to improve overall survival.

Advanced breast cancer incidence following population-based mammographic screening

BACKGROUND

Breast cancer mortality is declining in many Western countries. If mammography screening contributed to decreases in mortality, then decreases in advanced breast cancer incidence should also be noticeable.

PATIENTS AND METHODS

We assessed incidence trends of advanced breast cancer in areas where mammography screening is practiced for at least 7 years with 60% minimum participation and where population-based registration of advanced breast cancer existed. Through a systematic Medline search, we identified relevant published data for Australia, Italy, Norway, Switzerland, The Netherlands, U.K. and the U.S.A. Data from cancer registries in Northern Ireland, Scotland, the U.S.A. (Surveillance, Epidemiology and End Results (SEER), and Connecticut), and Tasmania (Australia) were available for the study. Criterion for advanced cancer was the tumour size, and if not available, spread to regional/distant sites.

RESULTS

Age-adjusted annual percent changes (APCs) were stable or increasing in ten areas (APCs of -0.5% to 1.7%). In four areas (Firenze, the Netherlands, SEER and Connecticut) there were transient downward trends followed by increases back to pre-screening rates.

CONCLUSIONS

In areas with widespread sustained mammographic screening, trends in advanced breast cancer incidence do not support a substantial role for screening in the decrease in mortality.

Why did the breast cancer lymph node status distribution improve in Denmark in the pre-mammography screening period of 1978-1994?

BACKGROUND

Danish breast cancer patients diagnosed in 1978-1994 experienced a trend over time towards a more favourable distribution of lymph node status at time of diagnosis, which was not due to mammography screening. We investigated how this trend could be explained by patient characteristics at diagnosis: age (biological processes), calendar period (e.g. environmental changes), birth cohort (living conditions over a life time), post-menopausal status (a predictor of less favourable nodal status), and tumour diameter (a marker of detection time).

MATERIAL AND METHODS

The data set consisted of 22 955 patients aged 30-69 years at time of diagnosis with known lymph node status, known tumour diameter, known menopausal status, and clinically detected tumours, available from the Danish Breast Cancer Cooperative Group (DBCG). Age, period, cohort, menopausal status, and tumour diameter were used as predictors in generalised linear models with either node-positive status (at least one of the excised lymph nodes being tumour-positive) or severely node-positive status (at least half of the excised lymph nodes being tumour-positive) as outcomes. Lymph node status was assessed both empirically and estimated using an EM algorithm in order to reduce misclassification.

RESULTS AND DISCUSSION

We found that the improved lymph node status distribution was most likely a period effect due to a combination of earlier detection of clinical tumours, explaining most of the trend in node-positive breast cancer and half of the trend in severely node-positive breast cancer, and some unknown factor affecting lymph node status but not necessarily other tumour characteristics.

Assessment of breast cancer opportunistic screening by clinical-pathological indicators: a population-based study

BACKGROUND

Although some clinical-pathological features of breast cancers, such as the incidence of ductal cancer in situ (DCIS) and the diameter of invasive tumours, are sensitive indicators of early detection, comprehensive population-based studies of opportunistic screening are needed.

METHODS

Cases of DCIS or invasive breast cancer diagnosed in 1996-2007 were identified from the Ticino Cancer Registry (south of Switzerland). Time trends of age-adjusted incidence and mortality, as well as main clinical-pathological features, such as tumour diameter, AJCC stage and histological grade, were analysed.

RESULTS

A total of 3047 incident cases of female breast cancer were identified. The proportion of DCIS with respect to invasive cases increased from 5.8% in the period 1996-2001 to 6.4% in the period 2002-2007. The median tumour size of invasive cancers decreased from 20 mm in 1996-2001 to 18 mm in 2002-2007 (P<0.0001). An increase in well/moderately differentiated invasive tumours, from 67% in the period 1996-2001 to 73% in 2002-2007 (P<0.001), was detected and resulted in an Annual Percentage Change of incidence of 2.8 (95% confidence interval: 1.3; 4.3).

CONCLUSION

An opportunistic screening strategy can lead to an improvement of prognostic features at diagnosis, but these features are still less favourable than those achieved by organised screening programmes.