Axillary nodal involvement by primary tumor features in early breast cancer: an analysis of 2600 patients

BACKGROUND

Primary tumor characteristics, which are readily available to all clinicians, may aid in selecting the optimal adjuvant therapy for patients with breast cancer (BC). Herein, we investigated the relationship between tumor size, hormone receptor and HER2 status, Ki67 and age with axillary lymph node metastases (ALNM) in early-BC patients.

METHODS

We analyzed data on consecutive 2600 early-BC cases collected in the registry of Fondazione IRCC Istituto Nazionale dei Tumori, Milano, Italy. Correlation between Ki67 and primary tumor size (T-size) was calculated by Spearman's rank correlation coefficient. Association of ALNM with Ki67 and other tumor characteristics was investigated by logistic regression. Adjusted odds ratios (ORs) with 95% confidence intervals (95% CIs) were estimated in all cases, and separately analyzed according to age, T-size and BC subtype.

RESULTS

Large tumor size strongly associated to ALNM, with an adjusted odds ratio (OR) for each 5-mm increase of 1.32 (95% CI 1.24-1.41), except for triple-negative BC (TNBC) cases. In tumors =10 mm, without lymphovascular invasion, representing the strongest predictor of ALNM (OR 6.09, 95% CI 4.93-7.53), Ki67 resulted particularly informative, with a fourfold increased odds of ALNM for values > 30%.

CONCLUSIONS

These results raise the question whether axillary node status is redundant in cases with exceptionally good features, i.e., small tumors with low Ki67, or in those candidate to adjuvant systemic treatment/radiotherapy anyway including TNBC, and support the incorporation of primary BC tumor characteristics as stratification factors in ongoing trials aiming at de-escalating axillary surgical procedures.

Abstract P4-08-05: Impact of common polymorphisms of CYP19A1 and UGT2B17 gene deletion on early endocrine-responsive postmenopausal breast cancer

Background Polymorphisms of genes involved in estrogen production have been linked to breast cancer risk, prognosis and treatment response. Polymorphisms of the aromatase gene CYP19A1 influence its activity. The UGT2B17 catalyzes glucuronic acid transfer to a variety of substrates, including steroids and drugs like the aromatase inhibitor exemestane. We investigated the impact of two variants of CYP19A1 (rs10046, rs4646) and the UGT2B17 gene deletion on disease outcome in 125 postmenopausal women operated for ER-positive primary breast cancer enrolled in a randomized pre-surgical trial.

Patients Briefly, upon informed consent, postmenopausal patients with ER-positive breast cancer (stage T1–2, N0–1, M0) eligible for surgery were randomized to receive either exemestane (25 mg/day), or celecoxib (800 mg/day), or placebo for 6 weeks prior to surgery at the European Institute of Oncology (2004-2008). Exemestane showed a significant 10% absolute reduction in Ki67 labeling index compared to the other two arms. Serum and whole blood was taken at baseline and the day before surgery and stored at -80°C until assayed.

Methods DNA was extracted from blood by QIAamp DNA Blood Kits. The CYP19A1 rs1004/rs46466 were analyzed by Taqman genotyping assays in real-time PCR. The UGT2B17 deletion was estimated by copy number assay (Lifetechnologies). Serum estradiol (E2) and estrone (E1) levels were measured by gas chromatography tandem mass spectrometry detection (GS-MS/MS) after liquid-liquid extraction. The lower limit of quantitation were 0.625 pg/mL for estradiol and 1.56 pg/mL for estrone. The association of genetic polymorphisms with “any event” was assessed by the Cox proportional hazards models adjusted for confounders.

Results The genetic polymorphisms did not deviate from Hardy-Weinberg equilibrium (P-value >0.41) and minor allele frequency of rs10046 (A/G), rs4646 (C/A), and UGT2B17Del were 0.45, 0.22, and 0.31, respectively. The rs10046 A and rs4646 C alleles were associated with higher estrogen levels. Carriers of rs10046 AA had median levels of 7.57 pg/ml E2 and 35.9 pg/mL E1 versus 3,9 pg/mL E2 and 27.4 E1 pg/mL in CA/AA genotypes (P<0.003). Carriers of rs4646 CC had 5.6 pg/ml E2 and 30.45 pg/mL E1 versus 3,95 pg/mL E2 and 27.4 E1 pg/mL in CA/AA genotypes (P=0.05 only for E1). After 6 weeks treatment with exemestane, we observed steeper decreases in estrogen levels in the rs10046 AA/rs4646 CC carriers (P=0.02 for E2). After a median follow-up of 7 years we found that women carrying at least one SNP of rs10046 and one SNP of rs4646 had a better prognosis compared with women carrying homozygote wt SNPs (HR=0.44; 95% CI: 0.2-0.99 P=0.049). Similarly, the UGT2B17 deletion was associated with a better prognosis (HR= 0.43; 95% CI: 0.19-0.97; P=0.0439). There was no interaction with pre-surgical or adjuvant treatment.

Conclusions Our analysis confirms previous findings of an association of CYP19A1 rs10046/rs4646 with estrogen levels in postmenopausal women. Interestingly, the carriers of the variants associated with lower estrogen levels at diagnosis had better prognosis. Further genomic profiling in larger trials aimed to enhance tailored treatment efficacy in endocrine-responsive postmenopausal breast cancer are warranted.

Citation Format: Johansson H, Gandini S, Aristarco V, Macis D, Guerrieri-Gonzaga A, Serrano D, Pruneri G, Lazzeroni M, Viale G, Toesca A, Rajasekaran A, Bonanni B, DeCensi A. Impact of common polymorphisms of CYP19A1 and UGT2B17 gene deletion on early endocrine-responsive postmenopausal breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-08-05.

Abstract P2-04-01: Withdrawn

This abstract was withdrawn by the authors.

Abstract P2-05-01: Whole genome sequencing reveals enrichment of mutations in mucin gene family in breast cancer diagnosed during pregnancy

Background

Pregnancy is known to modulate breast cancer (BC) risk. Different reproductive behaviors have been shown to impact not only the risk of developing BC but also the phenotypes of these tumors. Breast cancer diagnosed during pregnancy (BCP) is a rare disease but could serve as a good model to understand how pregnancy modulates BC biology. In this project, we aim to interrogate the effect of pregnancy on the biology of BC by performing whole genome sequencing (WGS) using a unique series of BC patients diagnosed during pregnancy (BCP).

Method

Whole genome sequencing was performed for 35 BCP and 20 non-pregnant controls matched for age and stage with available clinic-pathological data. DNA extracted from primary tumor and matched adjacent normal FFPE tissues was assessed using WGS on Illumina HiSeqXTen platform targeting 60x and 30x coverage for tumor and normal DNA respectively. Briefly, 2x150bp paired end sequence data were generated, cleaned, trimmed and aligned to the reference genome (hg19) using bwa-mem. Somatic mutations were detected using Strelka and annotated using SnpEff. Mutational signatures were extracted using deconstructSigs. Differences on mutational profiles between BCP and case controls were assessed using Wilcoxon test for continuous variables and Fisher exact test for categorical variables.

Result

No difference in clinic-pathological features was observed between BCP and control patients. A median of 10084 and 13829 SNVs and of 26 and 21 indels were identified in the BCP and controls respectively, no significant difference between the two groups being observed (p = 0.703 and p = 0.851). Of interest, a significantly higher number of mutations was found in the BCP as compared to the control group when considering only mutations associated with a deleterious effect (median: 20 vs. 12, p = 0.027). As expected, TP53 and PIK3CA were the most frequently mutated genes both in BCP and control cases without any significant difference between the groups (34.3% vs. 22.2%, p = 0.53 and 20.0% vs. 16.7%, p = 1, respectively). Interestingly, there was a significant enrichment of non-silent mutations in the mucin genes family (MUC2, MUC4, MUC12, MUC16, MUC17, MUC20) in the BCP group: 45.7% of BCP vs. 11.1% of control cases had at least one such mutation (p = 0.015). A similar significant result (45.7% vs. 23.1%, p = 0.034) was found when comparing BCP with BC control cases from the TCGA dataset (selected to have similar age, ER and PR distribution, N = 56). When comparing the distribution of the twelve BC mutational signatures, a borderline significant enrichment with a signature depicting mismatch-repair deficiency (signature 20) was observed in the BCP patients (p = 0.059).

Conclusion

This is the first study reporting the mutational landscape of breast cancer diagnosed during pregnancy using WGS. We found that BCP are associated with a higher number of putative driver mutations including mutations in mucin genes, shown to be implicated in tumorigenesis. Furthermore, BCP were enriched with a mismatch-repair deficiency signature. These results could open new avenues for the development of targeted therapeutic approaches for patients diagnosed with breast cancer during pregnancy.

Citation Format: Nguyen B, Venet D, Desmedt C, Pruneri G, Peccatori F, Mardis ER, Azim HA, Rothé F, Sotiriou C. Whole genome sequencing reveals enrichment of mutations in mucin gene family in breast cancer diagnosed during pregnancy [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-05-01.

Abstract P4-15-06: Low dose tamoxifen lowers recurrences after mastectomy for in situ neoplasia. Ten-year results of a monoinstitutional study

There is no agreement upon the need of a preventive treatment after breast mastectomy for in situ neoplasia. Low-dose tamoxifen (5 mg/day) has comparable antiproliferative effect than the standard dose of 20 mg/day in biomarker trials and has been shown to halve ipsilateral recurrence in a large cohort of postmenopausal ER positive DCIS treated with breast conserving surgery (Guerrieri-Gonzaga et al., Int J Cancer 2016).

Here we investigated the effect of low dose tamoxifen in patients treated with mastectomy for an in situ neoplasia and followed-up in a single Institution for a median of 10 years.

Our cohort consists of 404 consecutive premenopausal (n=281) or postmenopausal (n=123) women who underwent unilateral mastectomy at the European Institute of Oncology (IEO), with or without nipple preservation, between 1996 and 2011. Patients had a diagnosis of pure LCIS (n=12) or ER positive (ER>1%) DCIS (n=363) or both (n=29) and were treated with tamoxifen 5 mg/day (n=162) or no treatment (n=242) upon medical judgment, patient preference and/or clinical trial assignment. The main subject and tumor characteristics are reported in table 1.

Patient and tumor characteristics No tam (n=242)Low dose tam (n=162)P-valueMedian age, years (IQR)46 (41, 54)47 (42, 51)0.65Premenopausal status (n, %)160 (66)121 (75)0.07Median BMI (kg/m2, IQR)22 (20, 25)22 (20, 24)0.7Breast cancer family history (%)29320.44Histology (LCIS, DCIS, both; %)4/92/42/86/120.01Grading (G1,G2,G3;%)11/59/2918/61/200.04Median ER (%, IQR)90 (70, 95)90 (80, 95)0.005Median PgR (%, IQR)40 (5, 80)68 (25, 90)0.0002Median Ki67 (%, IQR)15 (10, 23)14 (10, 20)0.03Radiotherapy (n, %)95 (39)76 (47)0.13

After a median follow-up of 10 years (range 4-21 years) and a median low dose tamoxifen treatment of 4.9 years (IQR 2.7, 5.0), a total of 85 events were observed (28 in situ, 40 invasive breast cancers, 3 metastatic diseases, 12 other primary cancers, 2 deaths). A total of 36 ipsilateral breast events (23 versus 13 in the no tam versus tam group, respectively), 32 contralateral breast events (22 versus 10 in the no tam versus tam, respectively) and 17 other events (11 versus 6 in the no tam versus tam, respectively) occurred. Overall, eleven deaths (3%) occurred and no endometrial cancers were observed. A time-dependent competing risk model was applied for tamoxifen use and we have shown that low-dose tamoxifen was associated with a 48% reduction on all breast events (adjusted HR=0.52, 95% CI: 0.31–0.88, p=0.01), adjusting for radiotherapy and age.

Although limited by the observational nature of the study, we show for the first time that treatment with low dose tamoxifen is effective and safe in women who underwent mastectomy for non-invasive breast neoplasms and should be taken into consideration as a risk reduction strategy for premenopausal and postmenopausal women with breast intraepithelial neoplasia.

Citation Format: Guerrieri-Gonzaga A, Gandini S, Serrano D, Lazzeroni M, Pruneri G, Varricchio C, Cazzaniga M, Leonardi MC, Galimberti V, Viale G, De Censi A, Bonanni B. Low dose tamoxifen lowers recurrences after mastectomy for in situ neoplasia. Ten-year results of a monoinstitutional study [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-15-06.

The prevalence and clinical relevance of tumor-infiltrating lymphocytes (TILs) in ductal carcinoma in situ of the breast

Background

Tumor-infiltrating lymphocytes (TILs) are a robust prognostic adjunct in invasive breast cancer, but their clinical role in ductal carcinoma in situ (DCIS) has not been ascertained.

Patients and methods

We evaluated the prevalence and clinical relevance of TILs in a well annotated series of 1488 consecutive DCIS women with a median follow-up of 8.2 years. Detailed criteria for TILs evaluation were pre-defined involving the International Immuno-Oncology Biomarker Working Group. TILs percentage was considered both as a continuous and categorical variable. Levels of TILs were examined for their associations with ipsilateral breast event (IBE), whether in situ or invasive.

Results

Of the 1488 patients with DCIS under study, 35.1% had <1%, 58.3% 1-49% and 6.5% ≥50% peri-ductal stromal lymphocytes. The interobserver agreement in TILs evaluation, measured by the intraclass correlation coefficient (ICC) was 0.96 (95% CI 0.95-0.97). At univariable analysis, clinical factors significantly associated with TILs (P ≤0.001) were intrinsic subtype, grade, necrosis, type of surgery. Her-2 positive DCIS were more frequently associated with TILs (24% of patients with TILs ≥50%), followed by the triple negative (11%), Luminal B/Her-2 positive (9%) and Luminal A/B subtypes (1%) (P < 0.0001). We did not find any association between TILs as a continuous variable and the risk of IBEs. Likewise, when patients were stratified by TILs percentage (<1%, between 1% and 49.9%, and ≥50%), no statistically significant association was observed (10-year cumulative incidence of IBEs: 19%, 17.3%, and 18.7% respectively, P = 0.767).

Conclusion

TILs occur more frequently in the Her-2 positive DCIS. Although we did not find a significant association between TILs and the 10-year risk of IBE, our data suggest that immunotherapies might be considered in subsets of DCIS patients.