Abstract PS6-36: The formation of GCs in cancer-free ALNs, a non-monotonic prognostic factor in HR-negative invasive breast cancer patients

Abstract

Abstract Purpose: To assess the frequency and prognostic relevance of germinal centres (GC) in cancer-free axillary lymph nodes (ALNs), in relation to stromal tumour-infiltrating lymphocytes (sTILs) and the presence of tertiary lymphoid structures (TLS) in the primary carcinoma, in LN-positive Hormone Receptor (HR)-negative invasive breast cancer patients. Patients and methods: A cohort of 161 patients with HR-negative invasive breast cancer of no special type (NST) and LN-positive status treated between 2005-10 at Tianjin Medical University (China) was identified. sTILs and TLS at the primary tumour site and GC in 2,841 involved and cancer-free ALNs were evaluated on H&E stained sections. Markers were tested for prognostic value for invasive Disease-Free Survival (iDFS), distant Disease-Free Survival (dDFS) and Overall Survival (OS), using Cox regression models adjusted for clinico-pathological factors. Results: Among the 161 HR-negative breast cancers, 47% (n=75) had >=20% sTILs and 24% (n=38) peritumoural TLS. 75% (121/161) and 76% (122/161), respectively, displayed GCs in their cancer-free and involved ALNs. Significantly higher numbers of GCs were seen in both cancer-free and involved ALNs when the primary tumours showed >=20% sTILs. The presence of TLS was significantly associated with increased GC numbers in involved but to a lesser extend in cancer-free ALNs (Kruskal-Wallis rank sum test, p<0.001 and P_value=0.07, respectively). As expected, increased sTILs and presence of TLS were associated with improved outcome for all endpoints. Using an iterative process to determine an optimal cut off point by a minimal P value approach, a non-monotonic relationship between the frequency of GC in cancer-free ALNs and all endpoints was observed. Patients with >2 GC but less than the top 5% (= 62 GC) in cancer-free ALNs showed improved iDFS, dDFS and OS, whilst patients with <=2 GC or >62 GC across all assessed cancer-free ALNs had poorer iDFS, dDFS and OS (see Table). In the multivariate models, the frequency of GC in cancer-free ALNs added independent prognostic information for all endpoints across all patients. In patients with >=20% sTILS, cancer-free ALNs within the top 5% for GC remained associated with a worse dDFS and iDFS (see Table). Cancer-free ALNs with <=2 GC in total identified a subgroup of patients with <20% sTILs tumours having the worst iDFS, dDFS and OS in multivariate models. Five-year iDFS, dDFS and OS in patients with <20% sTILs were 39%, 39% and 48% respectively for those with <=2 GC in total, in comparison those with >2 GC whose five-year iDFS, dDFS and OS were 65%, 65% and 69%, respectively. Conclusions: The prognostic importance of GC assessment in cancer-free ALNs in women with LN-positive HR-negative breast cancers is demonstrated. A better outcome in patients with GC formation in their cancer-free ALNs, despite low sTILs in the primary carcinoma, may suggest a systemic anticancer immune response. High sTILs but with extreme GC formation in the cancer-free ALNs could potentially reflect an overdriving but less effective immune response. The assessment of the combination of primary and nodal immune response in HR-negative breast cancers is imperative in these high-risk patients. Table 1. Univariate and Multivariate Cox Regression Analysis of Outcome by GC in Cancer-Free ALNsiDFSUnivariateAll cases<20% sTIL>=20% sTILTotal GCs number - binnedModel PHRCIModel PHRCIModel PHRCI<=23.581.95 - 6.572.871.48 - 5.571.310.15 - 11.262>GC<624.86E-05reference7.64E-03reference4.66E-03reference>624.631.75 - 12.41.930.26 - 14.5612.793.34 - 48.97MultivariateCorrected for: pNstage, sTILS & TLSCorrected for: pTstage & TLSCorrected for: pNstageTotal GCs number - binnedCovariate PModel PHRCICovariate PModel PHRCICovariate PModel PHRCI<=22.90E-022.00E-082.102.08 - 4.103.13E-037.00E-042.831.42 - 5.658.45E-011.00E-031.240.14 - 10.622>GC<62NAreferenceNAreferenceNAreference>624.15E-059.583.25 - 28.201.94E-014.070.49 - 33.876.62E-038.861.83 - 42.82dDFSUnivariateAll cases<20% sTIL>=20% sTILTotal GCs number - binnedModel PHRCIModel PHRCIModel PHRCI<=24.762.48 - 9.143.681.82 - 7.432,130.22 - 20.442>GC<622.46E-06reference1.10E-03reference2.19E-03reference>625.872.14 - 16.082.490.32 - 19.0718.434.04 - 84.03MultivariateCorrected for: pTstage, pNstage, sTILS & TLSCorrected for: Age, pTstage, TLSCorrected for: pNstageTotal GCs number - binnedCovariate PModel PHRCICovariate PModel PHRCICovariate PModel PHRCI<=24.30E-033.00E-092.911.40 - 6.059.01E-042.00E-053.451.66 - 7.165.51E-011.00E-031.990.21 - 19.132>GC<62NAreferenceNAreferenceNAreference>622.49E-0615.304.91 - 47.635.19E-028.610.98 - 75.553.11E-0313.302.39 - 73.89OSUnivariateAll cases<20% sTIL>=20% sTILTotal GCs number - binnedModel PHRCIModel PHRCIModel PHRCI<=24.142.03 - 8.412.931.38 - 6.223.130.28 - 34.512>GC<622.62E-04reference1.78E-02reference7.52E-02reference>624.131.18 - 14.42.570.33 - 19.8311.891.65 - 85.45MultivariateCorrected for: Age, pTstage, pNstage, sTILS & TLSCorrected for: Age & TLSCorrected for: pNstage, LVI & TLSTotal GCs number - binnedCovariate PModel PHRCICovariate PModel PHRCICovariate PModel PHRCI<=21.50E-013.00E-091.820.80 - 4.122.28E-024.00E-042.411.13 - 5.12*3.00E-04**2>GC<62NAreferenceNAreferenceNAreference>628.62E-0516.064.02 - 64.247.01E-027.050.85 - 58.342.80E-012.970.41 - 21.43*too few events Citation Format: Fangfang Liu, Thomas Hardiman, Patrycja Gazinska, Jelmar Quist, Sarah Pinder, Anita Grigoriadis. The formation of GCs in cancer-free ALNs, a non-monotonic prognostic factor in HR-negative invasive breast cancer patients [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS6-36.