Increasing incidence of breast cancer: distinguishing between the effects of birth cohort and a national breast screening programme

Change in mammographic density across birth cohorts of Dutch breast cancer screening participants

High mammographic density is a well‐known risk factor for breast cancer. This study aimed to search for a possible birth cohort effect on mammographic density, which might contribute to explain the increasing breast cancer incidence. We separately analyzed left and right breast density of Dutch women from a 13‐year period (2003–2016) in the breast cancer screening programme. First, we analyzed age‐specific changes in average percent dense volume (PDV) across birth cohorts. A linear regression analysis (PDV vs. year of birth) indicated a small but statistically significant increase in women of: 1) age 50 and born from 1952 to 1966 (left, slope = 0.04, p = 0.003; right, slope = 0.09, p < 0.0001); 2) age 55 and born from 1948 to 1961 (right, slope = 0.04, p = 0.01); and 3) age 70 and born from 1933 to 1946 (right, slope = 0.05, p = 0.002). A decrease of total breast volume seemed to explain the increase in PDV. Second, we compared proportion of women with dense breast in women born in 1946–1953 and 1959–1966, and observed a statistical significant increase of proportion of highly dense breast in later born women, in the 51 to 55 age‐groups for the left breast (around a 20% increase in each age‐group), and in the 50 to 56 age‐groups for the right breast (increase ranging from 27% to 48%). The study indicated a slight increase in mammography density across birth cohorts, most pronounced for women in their early 50s, and more marked for the right than for the left breast.

What's new?

Women with dense breast tissue are at increased risk of breast cancer. Here, changes in mammographic density were investigated across birth cohorts in women enrolled in a breast cancer screening program in the Netherlands. The findings reveal an increase in the average fraction of dense tissue in the breast across cohorts. In particular, greater breast density was observed in a higher proportion of women in later‐born than earlier‐born birth cohorts. The increase was most significant among women in their early 50s and may be linked to a reported shift toward older age at menopause among women in Europe.

Absence of sustained breast cancer incidence inflation in a national mammography screening programme

OBJECTIVE

To investigate the impact of population mammography screening on breast cancer incidence trends in New Zealand.

METHODS

Trends in age-specific rates of invasive breast cancer incidence (1994-2014) were assessed in relation to screening in women aged 50-64 from 1999 and 45-69 following the programme age extension in mid-2004.

RESULTS

Breast cancer incidence increased significantly by 18% in women aged 50-64 compared with 1994-98 (p<0.0001), coinciding with the 1999 introduction of mammography screening, and remained elevated for four years, before declining to pre-screening levels. Increases over 1994-99 incidence occurred in the 45-49 (21%) and 65-69 (19%) age groups following the 2004 age extension (p<0.0001). Following establishment of screening (2006-10), elevated incidence in the screening target age groups was compensated for by lower incidence in the post-screening ⩾70 age groups than in 1994-98. Incidence in women aged ⩾45 was not significantly higher (+5%) after 2006 than in 1994-98. The cumulated risk of breast cancer in women aged 45-84 for 1994-98 was 10.7% compared with 10.8% in 2006-10.

CONCLUSIONS

Increases in breast cancer incidence following introduction of mammography screening in women aged 50-64 did not persist. Incidence inflation also occurred after introduction of screening for age groups 45-49 and 65-69. The cumulated incidence for women aged 45-84 over 2006-10 after screening was well established, compared with 1994-98 prior to screening, shows no increase in diagnosis. Over-diagnosis is not inevitable in population mammography screening programmes.

BRCA1 Gene Mutation Screening for the Hereditary Breast and/or Ovarian Cancer Syndrome in Breast Cancer Cases: a First High Resolution DNA Melting Analysis in Indonesia

Specific patterns of the hereditary breast and ovarian cancer (HBOC) syndrome are related to mutations in the BRCA1 gene. One hundred unrelated breast cancer patients were interviewed to obtain clinical symptoms and signs, pedigree and familial history of HBOC syndrome related cancer. Subsequently, data were calculated using the Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm (BOADICEA) risk prediction model. Patients with high score of BOADICEA were offered genetic testing. Eleven patients with high score of BOADICEA, 2 patients with low score of BOADICEA, 2 patient's family members and 15 controls underwent BRCA1 genetic testing. Mutation screening using PCR-HRM was carried out in 22 exons (41 amplicons) of BRCA1 gene. Sanger sequencing was subjected in all samples with aberrant graph. This study identified 10 variants in the BRCA1 gene, consisting of 6 missense mutations (c.1480C>A, c.2612C>T, c.2566T>C, c.3113A>G, c.3548 A>G, c.4837 A>G), 3 synonymous mutations (c.2082 C> T, c.2311 T> C and c.4308T>C) and one intronic mutation (c.134+35 G>T). All variants tend to be polymorphisms and unclassified variants. However, no known pathogenic mutations were found.

Higher incidence of premenopausal breast cancer in less developed countries; myth or truth?

Background

Fundamental etiologic differences have been suggested to cause earlier onset of breast cancer in less developed countries (LDCs) than in more developed countries (MDCs). We explored this hypothesis using world-wide breast cancer incidence data.

Methods

We compared international age-standardized incidence rates (ASR) of pre- (<50 years) and postmenopausal (≥50 years) breast cancers as well as temporal trends in ASRs of pre-and postmenopausal breast cancer among selected countries during 1975–2008. We used joinpoint log-linear regression analysis to estimate annual percent changes (APC) for premenopausal and postmenopausal breast cancer in the northern Europe and in Black and White women population in the US.

Results

Premenopausal breast cancers comprised a substantially higher proportion of all incident breast cancers in LDCs (average 47.3%) compared to MDCs (average 18.5%). However, the ASR of premenopausal breast cancer was consistently higher in MDCs (29.4/100,000) than LDCs (12.8/100,000). The ASR of postmenopausal cancer was about five-fold higher in the MDCs (307.6/100,000) than the LDCs (65.4/100,000). The APC of breast cancer in Denmark was substantially higher in postmenopausal (1.33%) than premenopausal cancer (0.98%). Higher incidence of breast cancer among the white than black women in the US was pertained only to the postmenopausal cancer.

Conclusion

The substantial and consistent lower age-specific incidence of breast cancer in LDCs than in MDCs contradicts the theory of earlier onset. Demographic differences with fewer old women in LDCs and lower prevalence of risk factors of postmenopausal cancer are the most likely explanation to the lower mean age at diagnosis in these countries.

Immediate and delayed effects of mammographic screening on breast cancer mortality and incidence in birth cohorts

BACKGROUND

Trend studies investigating the impact of mammographic screening usually display age-specific mortality and incidence rates over time, resulting in an underestimate of the benefit of screening, that is, mortality reduction, and an overestimate of its major harmful effect, that is, overdiagnosis. This study proposes a more appropriate way of analysing trends.

METHODS

Breast cancer mortality (1950-2009) and incidence data (1975-2009) were obtained from Statistics Netherlands, 'Stg. Medische registratie' and the National Cancer Registry in the Netherlands for women aged 25-85 years. Data were visualised in age-birth cohort and age-period figures.

RESULTS

Birth cohorts invited to participate in the mammographic screening programme showed a deflection in the breast cancer mortality rates within the first 5 years after invitation. Thereafter, the mortality rate increased, although less rapidly than in uninvited birth cohorts. Furthermore, invited birth cohorts showed a sharp increase in invasive breast cancer incidence rate during the first 5 years of invitation, followed by a moderate increase during the following screening years and a decline after passing the upper age limit.

CONCLUSION

When applying a trend study to estimate the impact of mammographic screening, we recommend using a birth cohort approach.

Addressing the younger age at onset in breast cancer patients in Asia: an age-period-cohort analysis of fifty years of quality data from the international agency for research on cancer

Introduction. There is an established fact that Asian breast cancer patients are, on average, younger than their European counterparts. This study aimed to utilize the data from the Cancer Incidence in Five Continents I through XIII (published by the International Agency for Research on Cancer) to examine what contributes to the younger age at onset in the Asian population. Material and Methods. Data (number of breast cancer cases and corresponding population figures) for 29 registries in Europe and 9 registries in Asia for the period of 1953–2002 was accessioned and pooled to form two distinct populations, Asia and Europe. The age specific rates were defined and analyzed cross-sectionally (period wise) and longitudinally (cohort wise). The magnitude and the pattern of age specific rates were analyzed using the age-period-cohort analysis. The constrained generalized linear model with a priority assumption of cohort effect as contributing factor to changing rates was used to analyze the data. Result. During the last 50 years, the rate of breast cancer increased for both populations with an estimated annual percent change of 1.03% (with 95% CI of 1.029, 1.031) for Asia and 1.016% (95% CI of 1.015, 1.017) for Europe. There were stronger cohort effects in the magnitude of rates among the Asian population compared to the European population. The cohort effects, expressed as the rate ratio with cohort born in 1970 as reference, ranged from 0.06 (95% CI 0.05, 0.08) to 0.94 (95% CI 0.93, 0.96) for Asians and 0.35 (95% CI 0.33, 0.36) to 1.03 (95% CI 1.02, 1.04) for Europeans. The estimated longitudinal age specific rates (adjusted for cohort and period effects) showed similar patterns between the two populations. Conclusion. It was concluded that a strong cohort effect contributes to the younger age at onset among Asian breast cancer patients.

Descriptive epidemiology of breast cancer in Vojvodina

The main aim of our study was to perform the epidemiological analysis of the breast cancer in Autonomous Province of Vojvodina, Republic of Serbia, in 15 years period (1987-2001). Descriptive method was used in epidemiological analysis of the data from the Vojvodina cancer registry. According to our results the breast cancer is the most frequent neoplasm in women in Vojvodina (26.54% of all cancers), and the leading cause of mortality (20.97%). Linear trend for both incidence and mortality crude and standardized rates showed the significant and unfavorable increase from 1987 to 2001.

Recent trends and patterns in breast cancer incidence among Eastern and Southeastern Asian women

BACKGROUND

Incidence of breast cancer is rising in Asian countries, and breast cancer is the most common cancer among Asian women. However, there are few recent descriptive reports on the epidemiology of breast cancer among Eastern and Southeastern Asian populations.

METHODS

We examined incidence trends for invasive breast cancer in women aged ≥20 years from 15 registries in Eastern (China, Japan, the Republic of Korea, Taiwan) and Southeastern Asia (the Philippines, Singapore, Thailand) for the period 1993-2002 mainly using data from Cancer Incidence in Five Continents, Volumes VIII and IX. We compared trends in annual incidence rates and age-specific incidence curves over a 10-year period. We also compared the incidence rates of Asian-Americans with the rates of their Asian counterparts.

RESULTS

Breast cancer incidence rates increased gradually over time in all study populations. Rates were relatively high in Southeastern Asia and became progressively lower along a south-to-north gradient, with a fourfold geographic variation within the study populations. Age-specific incidence curves showed patterns that gradually changed according to incidence rates. Breast cancer incidence among Asian women living in the United States was 1.5-4 times higher than the corresponding incidence rate in the women's respective countries of origin.

CONCLUSION

Breast cancer incidence is expected to continue to increase for the next 10 years in Asia and may approach rates reported among Asian-Americans. The number and mean age of breast cancer cases is expected to increase as the female Asian population ages, the prevalence of certain risk factors changes (early menarche, late menopause, low parity, late age at first live birth, and low prevalence of breastfeeding), and as Asian countries introduce mass screening programs.

Use of multiple drains after mastectomy is associated with more patient discomfort and longer postoperative stay

BACKGROUND

Seromas constitute a common complication following surgery for breast cancer, and closed drainage is used routinely to reduce its incidence. The aim of this study was to evaluate the influence of number of drains on patient discomfort, seroma formation, and hospital stay during the immediate postoperative period after mastectomy for breast cancer.

PATIENTS AND METHODS

Based on a retrospective review of our clinical database, 110 consecutive patients from January 2004 through January 2006 who had undergone a mastectomy and axillary clearance for breast cancer were sent a simple postal questionnaire for collection of data.

RESULTS

A total of 70 patients responded (all women; mean age, 69.4 +/- 11.4 years). Twenty-seven patients (38.57%) had 3 drains implanted unilaterally, 24 (34.28%) had 2, and 19 (27.14%) had 1 drain. They were divided into 2 groups: the first group with 1 drain (19 patients) and the other with 2 or 3 drains (51 patients). Median postoperative hospital stay was 2 days (range, 1-8 days); patients with 1 drain had a significantly shorter postoperative hospital stay (median, 2 days [range, 1-4 days] vs. 2 days [range, 1-8 days]; Mann-Whitney U test, P = .02). A total of 15 patients (21.43%) complained of a seroma. There was no difference in seroma rates between groups. Patients who had a single drain implanted had a significantly lower rate of discomfort (median, 2 [range, 1-5] vs. 3 [range, 1-7]; Mann-Whitney U test; P = .04).

CONCLUSION

The number of drains used after a mastectomy for breast cancer did not significantly affect the rate or amount of seromas in this study, but the use of a single drain after mastectomy was significantly associated with less discomfort and shorter postoperative hospital stay.