Abstract P1-11-14: Breast conserving therapy and mastectomy revisited: overall and breast cancer-specific survival and the influence of age, stage, receptor status and comorbidities in 143,376 patients

This abstract was withdrawn by the authors.

FGF receptor genes and breast cancer susceptibility: results from the Breast Cancer Association Consortium

BACKGROUND

Breast cancer is one of the most common malignancies in women. Genome-wide association studies have identified FGFR2 as a breast cancer susceptibility gene. Common variation in other fibroblast growth factor (FGF) receptors might also modify risk. We tested this hypothesis by studying genotyped single-nucleotide polymorphisms (SNPs) and imputed SNPs in FGFR1, FGFR3, FGFR4 and FGFRL1 in the Breast Cancer Association Consortium.

METHODS

Data were combined from 49 studies, including 53 835 cases and 50 156 controls, of which 89 050 (46 450 cases and 42 600 controls) were of European ancestry, 12 893 (6269 cases and 6624 controls) of Asian and 2048 (1116 cases and 932 controls) of African ancestry. Associations with risk of breast cancer, overall and by disease sub-type, were assessed using unconditional logistic regression.

RESULTS

Little evidence of association with breast cancer risk was observed for SNPs in the FGF receptor genes. The strongest evidence in European women was for rs743682 in FGFR3; the estimated per-allele odds ratio was 1.05 (95% confidence interval=1.02-1.09, P=0.0020), which is substantially lower than that observed for SNPs in FGFR2.

CONCLUSION

Our results suggest that common variants in the other FGF receptors are not associated with risk of breast cancer to the degree observed for FGFR2.

Abstract P5-05-05: Lower mitotic activity in BRCA1/2-associated primary breast cancers occurring after risk-reducing salpingo-oophorectomy

Background Bilateral salpingo-oophorectomy reduces breast cancer (BC) risk by about 50% in BRCA1/2 mutation carriers when performed premenopausally. It has been hypothesized that growth activity of BCs originating after risk-reducing salpingo-oophorectomy (RRSO) is lower. We compared tumor characteristics and growth rates of BRCA1/2-associated primary BCs (PBCs) detected after RRSO with those of tumors originating without RRSO.

Methods From a cohort of 271 female BRCA1/2-associated patients with screen detected BC, 20 BRCA1/2 mutation carriers with PBC detected ≥12 months after RRSO were selected (RRSO group). Controls were 36 BRCA1/2 mutation carriers with PBC detected without RRSO (non-RRSO group) matched for age at PBC diagnosis (± 2.5 years) and for BRCA1 or BRCA2 mutation (intended matching ratio 1:2). Tumor growth rates, expressed as tumor volume doubling times (DT), were calculated. Pathology samples were revised for histological subtype, tumor differentiation grade, estrogen receptor (ER), progesterone receptor (PR) and HER2 status. Imaging examinations (magnetic resonance imaging (MRI), mammography) before and at BC diagnosis were revised.

Results Median age at PBC diagnosis was 52 years (range 35-67). MRI detected more BC than mammography in the RRSO-group as compared to the non-RRSO group (83% vs. 39%, P = 0.02). Tumor size at diagnosis was smaller in the RRSO group (11.0 mm vs. 17.0 mm, P = 0.01). Mitotic activity indexes (MAI) in the RRSO and non-RRSO group were 12 vs. 22 mitotic counts/2 mm2 (P = 0.02). No significant differences in differentiation grade, ER and HER2 status were found. PR-status was more often positive in the RRSO group without reaching statistical significance (38% vs. 13%, P = 0.07). Median DT in the RRSO group was 124 days (range 89-193) and 93 days (range 54-253) in the non-RRSO group (P = 0.47).

Conclusion BC occurring after RRSO in BRCA mutation carriers features a lower MAI, suggesting a less aggressive biological behavior. When confirmed in larger series, this may have consequences for BC screening protocols for BRCA1/2 mutation carriers after RRSO.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-05-05.

Substantial breast cancer risk reduction and potential survival benefit after bilateral mastectomy when compared with surveillance in healthy BRCA1 and BRCA2 mutation carriers: a prospective analysis

BACKGROUND

To prospectively assess the efficacy of bilateral risk-reducing mastectomy (BRRM) when compared with surveillance on breast cancer (BC) risk and mortality in healthy BRCA1 and BRCA2 mutation carriers.

PATIENTS AND METHODS

Five hundred and seventy healthy female mutation carriers (405 BRCA1, 165 BRCA2) were selected from the institutional Family Cancer Clinic database. Eventually, 156 BRCA1 and 56 BRCA2 mutation carriers underwent BRRM. The effect of BRRM versus surveillance was estimated using Cox models.

RESULTS

During 2037 person-years of observation (PYO), 57 BC cases occurred in the surveillance group versus zero cases during 1379 PYO in the BRRM group (incidence rates, 28 and 0 per 1000 PYO, respectively). In the surveillance group, four women died of BC, while one woman in the BRRM group presented with metastatic BC 3.5 years after BRRM (no primary BC), and died afterward, yielding a HR of 0.29 (95% CI 0.02-2.61) for BC-specific mortality.

CONCLUSIONS

In healthy BRCA1/2 mutation carriers, BRRM when compared with surveillance reduces BC risk substantially, while longer follow-up is warranted to confirm survival benefits.

Tumour characteristics, survival and prognostic factors of hereditary breast cancer from BRCA2-, BRCA1- and non-BRCA1/2 families as compared to sporadic breast cancer cases

AIM OF THE STUDY

Results on tumour characteristics and survival of hereditary breast cancer (BC), especially on BRCA2-associated BC, are inconclusive. The prognostic impact of the classical tumour and treatment factors in hereditary BC is insufficiently known.

METHODS

We selected 103 BRCA2-, 223 BRCA1- and 311 non-BRCA1/2 BC patients (diagnosis 1980-2004) from the Rotterdam Family Cancer Clinic. To correct for longevity bias, analyses were also performed while excluding index patients undergoing DNA testing 2 years after BC diagnosis. As a comparison group, 759 sporadic BC patients of comparable age at and year of diagnosis were selected. We compared tumour characteristics, the occurrence of ipsilateral recurrence (LRR) and contralateral BC (CBC) as well as distant disease-free (DDFS), BC-specific (BCSS) and overall survival (OS) between these groups. By multivariate modelling, the prognostic impact of tumour and treatment factors was investigated separately in hereditary BC.

RESULTS

We confirmed the presence of the particular BRCA1-phenotype. In contrast, tumour characteristics of BRCA2-associated BC were similar to those of non-BRCA1/2 and sporadic BC, with the exception of a high risk of CBC (3.1% per year) and oestrogen-receptor (ER)-positivity (83%). No significant differences between BRCA2-associated BC and other BC subgroups were found with respect to LRR, DDFS, BCSS and OS. Independent prognostic factors for BC-specific survival in hereditary BC (combining the three subgroups) were tumour stage, adjuvant chemotherapy, histologic grade, ER status and a prophylactic (salpingo-)oophorectomy.

CONCLUSIONS

Apart from the frequent occurrence of contralateral BC and a positive ER-status, BRCA2-associated BC did not markedly differ from other hereditary or sporadic BC. Our observation that tumour size and nodal status are prognostic factors also in hereditary BC implies that the strategy to use these factors as a proxy for ultimate mortality appears to be valid also in this specific group of patients.

Tumor characteristics and detection method in the MRISC screening program for the early detection of hereditary breast cancer

In the MRISC study, women with an inherited risk for breast cancer were screened by a 6-month clinical breast examination (CBE) and yearly MRI and mammography. We found that the MRISC screening scheme could facilitate early breast cancer diagnosis and that MRI was a more sensitive screening method than mammography, but less specific. In the current study we investigated the contribution of MRI in the early detection of breast cancer in relation to tumor characteristics. From November 1999 to October 2003, 1909 women were included and 50 breast cancers were detected, of which 45 were evaluable and included in the current study. We compared the characteristics of tumors detected by MRI-only with those of all other (non-palpable) screen-detected tumors. Further, we compared the sensitivity of mammography and MRI within subgroups according to different tumor characteristics. Twenty-two (49%) of the 45 breast cancers were detected by MRI and not visible at mammography, of which 20 (44%) were also not palpable (MRI-only detected tumors). MRI-only detected tumors were more often node-negative than other screen-detected cancers (94 vs. 59%; P=0.02) and tended to be more often <or=1 cm (58 vs. 31%; P=0.11). MRI was more sensitive than mammography for a wide spectrum of invasive tumor characteristics i.e., size, nodal status, histology, grade and ER status. Half of the breast cancers detected in this study were visible by MRI only and these tumors were smaller and significantly more often node-negative than other screen-detected tumors, suggesting that MRI makes an important contribution to the early detection of hereditary breast cancer.

Contralateral recurrence and prognostic factors in familial non-BRCA1/2-associated breast cancer

BACKGROUND

A higher incidence of contralateral breast cancer and ipsilateral recurrence has been reported in familial breast cancer than in sporadic cancer. This study investigated the influence of contralateral cancer and tumour stage on survival in patients with familial non-BRCA1/BRCA2-associated breast cancer.

METHODS

The incidences of contralateral breast cancer, ipsilateral recurrence, distant disease-free and overall survival were assessed in 327 patients from families with three or more breast and/or ovarian cancers, but no BRCA1 or BRCA2 gene mutation (familial non-BRCA1/2), and in 327 control subjects with sporadic breast cancer, matched for year and age at detection.

RESULTS

Mean follow-up was 7.3 years for patients with familial-non-BRCA1/2 cancers and 6.5 years for patients with sporadic breast cancer. Tumours were stage T1 or lower in 62.1 per cent of familial non-BRCA1/2 cancers versus 49.9 per cent in sporadic breast cancers (P = 0.003), and node negative in 55.8 versus 52.1 per cent, respectively (P = 0.477). After 10 years the incidence of metachronous contralateral breast cancer was 6.4 per cent for familial non-BRCA1/2 tumours versus 5.4 per cent for sporadic cancers. The rate of ipsilateral recurrence was not significantly increased (17.0 versus 14.2 per cent, respectively, at 10 years; P = 0.132). Tumour size (hazard ratio (HR) 1.02 per mm increase, P = 0.016) and node status (HR 2.6 for three or more involved nodes versus node negative, P = 0.017) were independent predictors of overall survival in the familial non-BRCA1/2 group, and in the whole group, whereas contralateral breast cancer (HR 0.7, P = 0.503) and risk-reducing contralateral mastectomy (HR 0.4, P = 0.163) were not.

CONCLUSION

Stage at detection was a key determinant of prognosis in familial non-BRCA1/2 breast cancer, whereas contralateral cancer was not. Risk-reducing contralateral mastectomy did not significantly improve survival, but early detection can. Decisions on breast-conserving treatment can be made on the same grounds in patients with familial and sporadic breast cancer.

Survival and prognostic factors in BRCA1-associated breast cancer

BACKGROUND

Studies comparing survival in BRCA1-associated and sporadic breast cancer (BC) report inconsistent results and frequently concern small sample sizes. Further, the prognostic impact of the classical tumour and treatment factors is unclear in BRCA1-associated BC.

PATIENTS AND METHODS

We selected 223 BC patients diagnosed between 1980 and 2001 within families with a deleterious germline BRCA1-mutation ascertained at the Rotterdam Family Cancer Clinic. To correct for ascertainment bias, the group of index patients undergoing DNA testing more than 2 years after BC diagnosis (n = 53) was separated from the other BRCA1-patients (n = 170). All BRCA1-associated patients were matched in a 1:2 ratio for age and year of diagnosis to sporadic BC patients. We compared the occurrence of ipsi- and contralateral BC (CBC) as well as distant disease-free (DDFS), BC-specific (BCSS) and overall survival (OS). By multivariate modelling, the prognostic impact of tumour and treatment factors was investigated separately in BRCA1-associated and sporadic breast cancers.

RESULTS

For the total group of 669 cases, the median follow-up was 5.1 years, the median age at diagnosis 39 years. We confirmed the existence of the typical BRCA1-associated tumour type and the high CBC incidence. No significant differences between BRCA1-associated and sporadic tumours were found with respect to ipsilateral BC recurrence (HR(mult) 0.7; P = 0.24), DDFS (HR(mult) 1.2; P = 0.37) or BC-specific survival (HR(mult) 1.3; P = 0.23). A trend towards a worse survival was found for BRCA1-associated ductal BC (HR(mult) 1.5, P = 0.07). Prognostic factors for BRCA1-associated BC were age at diagnosis, tumour size and morphology, and nodal status. Further, survival was non-significantly improved by systemic treatment and a bilateral salpingo-oophorectomy. No effect on survival of a contralateral prophylactic mastectomy was seen.

CONCLUSIONS

BRCA1-associated BC is characterised by specific tumour characteristics, a high incidence of CBC and a trend towards a worse survival for the ductal tumour type. Our observation that tumour size and nodal status are also prognostic factors for BRCA1-associated BC implies that the strategy to use these factors as a proxy for ultimate mortality, for instance in BC screening programmes or the consideration of (contralateral) preventive mastectomy, appears to be valid in this specific group of patients.