Failure pattern and survival after breast conserving therapy. Long-term results of the Danish Breast Cancer Group (DBCG) 89 TM cohort

Based on the results from the DBCG 82 trial, breast conserving therapy (BCT) has been implemented as standard in Denmark since 1989, and today constitutes more than 70% of the primary treatment. Our aim was to evaluate the implementation of BCT as a routine procedure in patients treated according to the DBCG 89 program and compare recurrence pattern and survival both overall and when separated in age groups, with the results from the randomized DBCG 82 TM trial.

MATERIAL AND METHODS

A total of 1847 patients treated between 1989 and 1999 were included in a retrospective population-based cohort study. Data from the DBCG database were completed via search through the Danish Pathology Data Bank and medical records.

RESULTS

Median follow-up time was 17 years. At 20 years the cumulative incidences of local recurrence (LR) and disease-specific mortality (DSM) were 15.3% and 25.8%, respectively. Twenty-year overall survival (OS) and recurrence-free survival were 63.7% and 43.1%, respectively. Subdivided by age groups cumulative incidences at 20 years were LR: 18.9%, 10.5% and 12.4%, and DSM: 28.9%, 18.9% and 28.4% in young (≤45 years), middle-aged (46-55 years) and older (≥56 years) women, respectively. In an adjusted analysis age maintained a significant and independent effect on both LR and DSM.

CONCLUSION

The DBCG 82 TM program was successfully implemented. The women treated with BCT in the DBCG 89 program displayed equal failure pattern and improved survival in comparison with women from the DBCG 82 TM protocol. Occurrence of first failure and mortality varied with age; demonstrated by increased risk of LR, DM and DSM in the young patients and increased risk of DM and DSM in the older patients, compared to the middle-aged patients.

Abstract P3-04-03: A seven-gene profile predicting benefit of postmastectomy radiotherapy independently of nodal status in high risk breast cancer

Background: Recommendations for postmastectomy radiotherapy (PMRT) are well established in patients estimated to have a high risk of loco-regional recurrence (LR) (e.g. tumor size > 5 cm or ≥ 4 positive lymph nodes). International recommendations for patients with 1–3 positive lymph nodes suggest that PMRT should be restricted to younger patients and patients with other poor prognostic features. However, large randomized trials, including the DBCG82 trials (Danish Breast Cancer Cooperative Group), have previously shown a substantial overall survival benefit after PMRT in patients with low risk of LR, and shown that the largest translation of LR reduction into breast cancer mortality reduction occurs within the most favorable prognosis group. Our hypothesis is that a more refined partitioning of patients likely to benefit from PMRT can be established through identification of genes whose transcription interacts with PMRT to modify the hazard of LR.

Material and methods: The DBCG82bc cohort constitutes high risk patients (tumor size > 5 cm and/or positive nodes and/or invasion in skin or pectoral fascia) diagnosed between 1983–89, treated with mastectomy and partial axillary lymph nodes dissection and randomized to +/− PMRT. From 267 DBCG82bc patients, frozen tumor samples were available. Whole genome arrays (Applied Biosystem Human Genome Survey Microarray v2.0®, Applied Biosystem, Foster City, USA) were successful in 195 samples. Genes, whose expression levels interacted with PMRT on the association with LR, were identified through a two step Cox Proportional Hazard model with lasso penalty. 11 node negative patients were excluded from the subsequent analysis of 184 node positive patients (1–3 pos. nodes: 102 pts, ≥ 4 pos. nodes: 82 pts).

Results: Seven genes were identified whose expression interact with the effect of PMRT, and a specialized index was generated based on the expression levels of these genes. Patients were ranked according to the size of the index, and divided into quartiles with 25% of the patients designated as having a “high index” and 75% a “low index”. Among patients not receiving PMRT, a low index was in both nodal groups (1–3 vs. ≥ 4 positive nodes) associated with a significantly higher risk of LR compared to patients with a high index. In both nodal groups, PMRT significantly reduced the risk of LR in patients with a low index; equalizing the risk to patients with a high index, who showed no additional LR reduction by PMRT. In the group of 1–3 positive nodes, PMRT raised the local control rate (LCR) after 10 years from 47.5 % to 91.8% in the low index group (p = 0.0001), whereas the change in the high index group was non-significant (92.3% vs. 100.0%). In the group of patients with ≥ 4 positive nodes, PMRT raised LCR from 16.6% to 80.0% in the low index group (p = 0.0001), and no effect on LCR was seen in the high index group (83.3% vs. 87.5%, n.s.).

Conclusion: A seven gene-profile attaining prognostic and predictive impact, irrespective of number of positive nodes, was identified. The profile allowed the identification of 25% of the patients not showing any additional benefit from PMRT in terms of LR. The gene-profile may provide a method to identify patients expected to benefit from PMRT.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-04-03.

Mannan-binding lectin (MBL) and MBL-associated serine protease 2 (MASP-2) genotypes in colorectal cancer

Mannan-binding lectin (MBL) and MBL-associated serine protease 2 (MASP-2) are key factors of the lectin pathway of complement activation. Polymorphisms of the MBL2 and MASP-2 genes affect serum levels of MBL and MASP-2. In patients with colorectal cancer (CRC), the MBL and MASP-2 serum levels are increased and high MASP-2 levels are associated with recurrence and poor survival, whereas low MBL levels predict post-operative pneumonia. It is not known whether these associations are genetically based. In this study, the MBL and MASP-2 genotypes are investigated in 593 patients with CRC and 348 healthy controls. The potential association between genetic profile and infections, recurrence and survival is evaluated. Four single-nucleotide polymorphisms (SNPs) of MBL2 were analysed using TaqMan assays, with characterization of MBL2 wildtype A, variants B, C and D and alleles H/L, Y/X and P/Q. The SNP D120G for MASP-2 was determined. Serum levels of MBL and MASP-2 were measured. The MBL2 and MASP-2 genotype distribution was similar among patients with CRC and healthy controls and MBL2 genotype significantly associated with MBL concentration in serum (P<0.0001). No significant association between MBL2/MASP-2 genotype and post-operative infectious complications (P=0.33 and 0.22), recurrent cancer or survival (P=0.74 and P=0.61 respectively) was found. Thus, the increased serum levels of MBL and MASP-2 found in patients with CRC are not explained for by genetic profiles. In contrast to what has been demonstrated for serum levels of MBL and MASP-2, the genotypes do not predict disease course of the CRC patients.

Impact of BCL2 and p53 on postmastectomy radiotherapy response in high-risk breast cancer. A subgroup analysis of DBCG82 b&c

PURPOSE

To examine p53 and BCL2 expression in high-risk breast cancer patients randomized to postmastectomy radiotherapy (PMRT).

PATIENTS AND METHODS

The present analysis included 1 000 of 3 083 high-risk breast cancer patients randomly assigned to PMRT in the DBCG82 b&c studies. Tissue microarray sections were stained with immunohistochemistry for p53 and BCL2. Median potential follow-up was 17 years. Clinical endpoints were locoregional recurrence (LRR), distant metastases (DM), overall mortality, and overall survival (OS). Statistical analyses included Kappa statistics, chi(2) or exact tests, Kaplan-Meier probability plots, Log-rank test, and Cox univariate and multivariate regression analyses.

RESULTS

p53 accumulation was not significantly associated with increased overall mortality, DM or LRR probability in univariate or multivariate Cox regression analyses. Kaplan-Meier probability plots showed reduced OS and improved DM and LRR probabilities after PMRT within subgroups of both p53 negative and p53 positive patients. Negative BCL2 expression was significantly associated with increased overall mortality, DM and LRR probability in multivariate Cox regression analyses. Kaplan-Meier probability plots showed a significantly improved overall survival after PMRT for the BCL2 positive subgroup, whereas practically no survival improvement was seen after PMRT for the BCL2 negative subgroup. In multivariate analysis of OS, however, no significant interaction was found between BCL2 and randomization status. Significant reductions in LRR probability after PMRT were recorded within both the BCL2 positive and BCL2 negative subgroups.

CONCLUSION

p53 was not associated with survival after radiotherapy in high-risk breast cancer, but BCL2 might be.