Abstract P5-08-09: Use of oral contraceptives and risk of breast cancer in BRCA1 and BRCA2 mutation carriers: An international prospective cohort study; for the studies of EMBRACE, GENEPSO, HEBON, kConFab and BCFR

This abstract was withdrawn by the authors.

Abstract P2-06-04: Breast cancer after Hodgkin lymphoma: Influence of endogenous and exogenous gonadal hormones on the radiation dose-response relationship

Background

After chest radiotherapy (RT) for Hodgkin lymphoma (HL), women experience a dose-dependent increased breast cancer (BC) risk. It is unknown whether endogenous and exogenous gonadal hormones affect the radiation dose-response relationship.

Methods

We conducted a nested case-control study among female 5-year HL survivors treated before 41 years between 1965-2000. Data were collected through medical records and questionnaires for 174 BC cases and 466 matched controls. RT charts, simulation films and mammography reports were used to estimate the radiation dose to the location of the breast tumor.

Results

The median interval between HL and BC diagnosis was 21.9 years. 98% of BC cases had received chest RT, compared to 92% of controls. We observed a linear radiation dose-response curve with an adjusted excess odd ratio (EOR) of 5.4%/Gray (95%CI:1.8%-13.37%). Women with menopause <30 years (caused by high-dose procarbazine or pelvic RT) had a lower BC risk (OR:0.13, 95%CI:0.03-0.54) than women with menopause ≥50 years. BC risk increased with 7.4% for each additional year of intact ovarian function after RT (P<0.001). Among women with an early menopause (<45 years), the use of hormone replacement therapy (HRT) for ≥2 years did not increase BC risk (OR:0.81, 95%CI:0.30-2.21). Endogenous and exogenous hormones did not statistically significantly modify the slope of the radiation dose-response relationship.

Conclusion

HRT use did not appear to increase BC risk in female HL survivors with a therapy-induced early menopause. Moreover, there was no evidence for interaction between RT dose and years with intact ovarian function or HRT use.

Citation Format: Krul IM, Opstal - van Winden AWJ, Aleman BMP, Janus CPM, van Eggermond AM, de Bruin ML, Hauptmann M, Krol ADG, Schaapveld M, Broeks A, Kooijman KR, Fase S, Lybeert ML, Zijlstra JM, van der Maazen RWM, Kesminiene A, Diallo I, de Vathaire F, Russell NS, van Leeuwen FE. Breast cancer after Hodgkin lymphoma: Influence of endogenous and exogenous gonadal hormones on the radiation dose-response relationship [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-06-04.

Abstract P5-17-06: Prognostic value of method of detection in primary pure DCIS

Background

Population-based mammographic screening programs have led to a substantial increase in incidence of ductal carcinoma in situ (DCIS). We assessed whether the method of detection provides prognostic information among women with DCIS detected through the Dutch screening program (screen-detected DCIS) and those with DCIS not detected within the national screening program (non-screen-detected DCIS). This could have impact on the treatment strategy of screen-detected DCIS as compared to symptomatic DCIS.

Methods

We studied a population-based retrospective cohort comprising 7,106 women aged 49-76 years with primary pure DCIS, who were treated by mastectomy or breast conserving surgery with or without radiotherapy between 1989 and 2004 in the Netherlands. Risk of subsequent ipsilateral and contralateral invasive breast cancer and overall survival among women with screen-detected (n=4,905) and non-screen-detected (n=2,201) DCIS were compared using Cox regression, adjusting for treatment (time-dependent), age (time-scale), diagnosis period and follow-up duration. Because of gradual implementation of the screening program in the Netherlands, we defined two periods based on year of DCIS diagnosis: 1989-1998 (gradual implementation of screening) and 1999-2004 (full coverage of screening).

Results

With a median follow-up of 10.5 years (interquartile range 7.7-14.0 years) 366 ipsilateral (screen-detected DCIS n=234, non-screen-detected DCIS n=132) and 380 contralateral (screen-detected DCIS n=245, non-screen-detected DCIS n=135) invasive breast cancers were diagnosed, and 1,088 of 7,106 women died (screen-detected DCIS n=603, non-screen-detected DCIS n=485). From 1989 to 2004 the number of non-screen-detected DCIS remained stable (mean 140, range 110-187 per year), whereas the number of screen-detected primary pure DCIS increased from 8 in 1989 to 596 in 2004. Ipsilateral invasive breast cancer risk was lower for screen-detected DCIS compared to DCIS not detected within the national screening program, irrespective of DCIS treatment, period of diagnosis, and follow-up duration (adjusted hazard ratio [HR] 0.74, 95% confidence interval [CI] 0.59-0.92, p < 0.01). The prognostic value of method of detection was similar across categories of treatment, period of diagnosis, and follow-up duration. The risk of contralateral invasive breast cancer did not differ between screen-detected DCIS and non-screen-detected DCIS (adjusted HR 0.89, 95% CI 0.71-1.11, p = 0.3) and neither did all-cause mortality (adjusted HR 0.91, 95% CI 0.79-1.04, p = 0.2).

Conclusion

Women with primary pure DCIS detected through the Dutch screening program had lower risk of subsequent ipsilateral invasive breast cancer, irrespective of DCIS treatment, compared to women whose DCIS was not detected within the national screening program. However, the magnitude of this risk difference does not warrant a different treatment strategy of screen-detected DCIS as compared to non-screen-detected DCIS. Having a screen-detected DCIS was not associated with risk of subsequent contralateral invasive breast cancer and all-cause mortality.

Citation Format: Elshof LE, Schaapveld M, Schmidt MK, van Leeuwen FE, Rutgers EJTh, Wesseling J. Prognostic value of method of detection in primary pure DCIS. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-17-06.

Abstract P5-16-02: Risk of subsequent ipsilateral invasive breast cancer after a primary diagnosis of ductal carcinoma in situ

Background

Since the introduction of population-based mammography screening the incidence of ductal carcinoma in situ of the breast (DCIS) has increased dramatically and concerns about overdiagnosis and overtreatment have been raised. DCIS is considered to be a precursor lesion of most invasive breast cancer, but the challenge remains to distinguish the progressive from the clinically indolent, i.e. harmless lesions. Therefore, we aim to assess the risk of developing a subsequent ipsilateral invasive breast cancer after a first cancer diagnosis of primary DCIS in a large cohort as a first step to solve this clinical dilemma.

Methods

We conducted a retrospective study using a nationwide cohort comprising 12,721 women with a first cancer diagnosis of breast carcinoma in situ in the Netherlands between 1 January 1989 and 31 December 2004 and follow-up data up to 31 December 2010, extracted from the Netherlands Cancer Registry (NCR). Women who had bilateral breast disease, a diagnosis other than pure DCIS, and patients who received chemo- or hormonal therapy for their DCIS were excluded, as well as patients who had any other previous cancer diagnosis except for non-melanoma skin carcinoma. Using data from NCR and PALGA, the Dutch Pathology Registry, information about treatment and outcomes was collected and analysed. Outcome was defined as a subsequent ipsilateral invasive breast cancer as first invasive recurrence. Women who had a contralateral invasive breast cancer first, were censored at this diagnosis date. Invasive recurrence rates were compared by age and treatment groups using Cox regression. Women were divided into three age groups: women who were within the age group eligible for participation in the Dutch screening programme, and women who were either younger or older.

Results

A total number of 10,276 women with pure DCIS were included. After a median follow-up of 11.6 years, 520 first ipsilateral invasive recurrences were identified. Preliminary results show that approximately half of the women were treated with breast-conserving surgery (BCS), and the other half underwent a mastectomy. Of the patients who underwent BCS, about half received additional radiotherapy (RT). The age-adjusted hazard ratio for ipsilateral invasive breast cancer in BCS only versus BCS + RT was 2.49 (95% CI: 1.99 – 3.12) and in mastectomy versus BCS + RT 0.32 (95% CI: 0.24 - 0.43). After adjusting for treatment, risk of subsequent ipsilateral invasive breast cancer was higher for women who were younger than the invitation age range for screening when diagnosed compared to women within the age group eligible for the Dutch screening programme (HR = 1.86; 95% CI: 1.51 – 2.29).

Conclusion

This unique nationwide DCIS cohort shows that young women and women treated with BCS only have an increased risk of developing a subsequent ipsilateral invasive breast cancer after a first cancer diagnosis of primary DCIS. Using this cohort with a large number of women with subsequent ipsilateral invasive breast cancer, we will subsequently evaluate the concordance of features of the primary DCIS and the subsequent invasive breast cancer, and the association of characteristics of the DCIS with the risk of developing invasive ipsilateral breast cancer.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-16-02.

Abstract A90: The attribution of lifestyle related risk factors in middle age on breast cancer incidence in The Netherlands: Preliminary results

Background: Breast cancer, especially postmenopausal, is one of the most common cancers in Western women. Although therapeutic options have improved, there still is a high mortality rate. Several of the known risk factors for breast cancer are lifestyle related and modifiable, providing an opportunity for primary prevention. Middle-aged women still have the chance to modify these factors to lower nearby breast cancer risk. We estimated the fraction of postmenopausal breast cancer cases that is attributable to lifestyle factors as currently present in middle-aged Dutch women.

Methods: We estimated population attributable fractions (PAFs) of five potentially modifiable risk factors for Dutch women aged 45-54 years. Risk factors included overweight and obesity, alcohol use, physical inactivity, current use of hormone replacement therapy (HRT) and oral contraceptives.

We based relative risks on literature search including meta-analyses and expert group consensus. Current prevalence rates of the risk factors were derived from several Dutch registration databases and national surveys (2009-2011).

Results: Of all 45-54 year old contemporary Dutch women, 46% are estimated to be physically inactive, 43% to be overweight or obese, 42% to drink alcohol, 1% to use HRT and 17% to use contraceptives.

These risk factors jointly account for an estimated 20.2% of all future breast cancer cases in these women. Physical inactivity and alcohol use are responsible for the highest population attributable fraction (PAF of 7.0% and 6.8% respectively), followed by overweight and obesity (4.3%), oral contraceptive use (3.4%) and hormone replacement therapy (0.6%).

Conclusion: On a population level, lifestyle related factors play an important role in the development of postmenopausal breast cancer. Considering current prevalence rates in the Netherlands, our findings imply that modifiable risk factors present at middle-age are jointly responsible for 1 out of every 5 future breast cancer cases. This is in concordance with other studies in European countries.

Our findings thus suggest that incidence rates can be lowered substantially by changing lifestyle habits, even in a woman's later life.

Citation Format: WAM van Gemert, SG Elias, RA Bausch-Goldbohm, PA van den Brandt, HG Grooters, E Kampman, LALM Kiemeney, FE van Leeuwen, EM Monninkhof, E De Vries, PHM Peeters. The attribution of lifestyle related risk factors in middle age on breast cancer incidence in The Netherlands: Preliminary results. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr A90.

S4-2: The Risk of Contralateral Breast Cancer in BRCA1/2 Carriers Compared to Non-BRCA1/2 Carriers in an Unselected Cohort

Background: Women who survived their first breast cancer have a higher risk to develop a new primary tumor in the contralateral breast than the risk of women in the general population to develop a first breast cancer. Especially women who carry a germline mutation in either the BRCA1 or the BRCA2 gene face a high lifetime risk of developing a synchronous or metachronous bilateral breast cancer. It is important to provide precise risk estimates of contralateral breast cancer and identify factors which predict the risk of CBC in this group of high risk women. To answer these questions, we looked at the effect of BRCA1/2-carriership and its interaction with other factors on the risk to develop a CBC in an unselected cohort of breast cancer patients. Materials and methods: We collected clinico-pathological, treatment and follow-up data for 4856 patients with unilateral, invasive breast cancer, diagnosed under the age of 50, between 1970 and 2003, in ten different hospitals throughout The Netherlands. Germline DNA was isolated from formalin-fixed paraffin-embedded tissue and patients were tested for the most prevalent pathogenic BRCA1 and BRCA2 mutations in The Netherlands. DNA and clinical data were coded before the analyses. All second primary breast tumors in the contralateral breast diagnosed more than 3 months after the diagnosis of the first breast cancer were considered as events. Preliminary results from life-table analysis and Cox Proportional Hazard models adjusted for age at diagnosis are shown here. Further statistical analyses will include competing risk analysis.

Results: In 4856 patients genotyped for BRCA1/2 mutations, 206 (4.2%) carriers were identified. During a median follow-up of 9.8 years (range 0–38), 9% of the patients developed a CBC, resulting in a cumulative 15-year risk for CBC of 10.4% (95% CI = 9.25−11.7) for non-carriers and 35.4% (95% CI = 25.9−46.9) for carriers of a BRCA1 or BRCA2 mutation (HR = 4.04 (95% CI = 2.88−5.68)). Patients carrying a BRCA1/2 mutation who were diagnosed under the age of 40 with their first breast cancer experienced a cumulative 15-year risk for CBC of 52.4% (95% CI = 36.4−70.3) versus 21.3% (95% CI = 12.0−36.0) in those over the age of 40 (HR = 0.30 (95% CI = 0.14−0.65)). Furthermore, BRCA1/2 mutation carriers with a triple negative first tumor had a cumulative risk for CBC of 43.6 (95% CI = 25.1−67.7), in contrast, BRCA1/2 mutation carriers with a non-triple negative first tumor had a cumulative risk for CBC of 13.4% (95% CI = 4.21−38.4) (HR = 0.24 (95% CI = 0.07−0.86)). Age at diagnosis and triple negative status were not found to be predictors of the risk of CBC in non-carriers (HR = 0.81 (95% CI = 0.53−1.24) and HR = 1.49 (95% CI = 0.91−2.41) respectively).

Discussion: In this study we identified subgroups of patients with a high risk to develop a CBC after their first breast cancer. Guidelines about treatment decisions and screening for follow-up should take into account these high risk subgroups to provide even better information and counseling for BRCA1/2 mutation carriers.

On behalf of more than 20 involved authors of the BOSOM study from 10 different hospitals and institutions throughout The Netherlands.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr S4-2.

Breast cancer and hormonal contraceptives: further results. Collaborative Group on Hormonal Factors in Breast Cancer

The Collaborative Group on Hormonal Factors in Breast Cancer has brought together and reanalysed the worldwide epidemiological evidence on breast cancer risk and use of hormonal contraceptives. Original data from 54 studies, representing about 90% of the information available on the topic, were collected, checked and analysed centrally. The 54 studies were performed in 26 countries and include a total of 53,297 women with breast cancer and 100,239 women without breast cancer. The studies were varied in their design, setting and timing. Most information came from case-control studies with controls chosen from the general population; most women resided in Europe or North America and most cancers were diagnosed during the 1980s. Overall 41% of the women with breast cancer and 40% of the women without breast cancer had used oral contraceptives at some time; the median age at first use was 26 years, the median duration of use was 3 years, the median year of first use was 1968, the median time since first use was 16 years, and the median time since last use was 9 years. The main findings, summarised elsewhere, are that there is a small increase in the risk of having breast cancer diagnosed in current users of combined oral contraceptives and in women who had stopped use in the past 10 years but that there is no evidence of an increase in the risk more than 10 years after stopping use. In addition, the cancers diagnosed in women who had used oral contraceptives tended to be less advanced clinically than the cancers diagnosed in women who had not used them. Despite the large number of possibilities investigated, few factors appeared to modify the main findings either in recent or in past users. For recent users who began use before age 20 the relative risks are higher than for recent users who began at older ages. For women whose use of oral contraceptives ceased more than 10 years before there was some suggestion of a reduction in breast cancer risk in certain subgroups, with a deficit of tumors that had spread beyond the breast, especially among women who had used preparations containing the highest doses of oestrogen and progestogen. These findings are unexpected and need to be confirmed. Although these data represent most of the epidemiological evidence on the topic to date, there is still insufficient information to comment reliably about the effects of specific types of oestrogen or of progestogen. What evidence there is suggests, however, no major differences in the effects for specific types of oestrogen or of progestogen and that the pattern of risk associated with use of hormonal contraceptives containing progestogens alone may be similar to that observed for preparations containing both oestrogens and progestogens. On the basis of these results, there is little difference between women who have and have not used combined oral contraceptives in terms of the estimated cumulative number of breast cancers diagnosed during the period from starting use up to 20 years after stopping. The cancers diagnosed in women who have used oral contraceptives are, however, less advanced clinically than the cancers diagnosed in never users. Further research is needed to establish whether the associations described here are due to earlier diagnosis of breast cancer in women who have used oral contraceptives, to the biological effects of the hormonal contraceptives or to a combination of both. Little information is as yet available about the effects on breast cancer risk of oral contraceptive use that ceased more than 20 years before and as such data accumulate it will be necessary to re-examine the worldwide evidence.