Abstract P1-09-04: Use of adjuvant chemotherapy and outcomes in women 70 years and older with HER-2 positive or triple negative breast cancer

Background: Chemotherapy use decreases with increasing age. There is a stronger rationale for adjuvant chemotherapy in HER-2 positive (HER2+) and triple negative (TN) breast cancer (BC) due to a higher risk of recurrence, known benefit of trastuzumab with chemotherapy and lack of other systemic options.

Aims: 1) Compare outcomes of resected HER2+ and TN BC in older women (age ≥70) (OW) vs. younger women (age 50-69) (YW) 2) Determine chemotherapy use in OW vs. YW 3) Explore factors associated with chemotherapy use in women with HER2+ and TN BC and determine how these factors differ by age group (OW vs. YW)

Methods: Women ≥50 years old with newly diagnosed resected HER2+ or TN stage I-III BC in British Columbia from 2003-2006 were included. Data on comorbidity, performance status, and reason for no chemotherapy was gathered via chart review of OW. Kaplan-Meier curves for relapse-free survival (RFS), breast cancer-specific survival (BCSS) and overall survival (OS) were calculated. Logistic regression was used to model the likelihood of receiving chemotherapy and Cox proportional hazards was used to model BCSS and OS.

Results: OW (n = 292) had larger tumors (p = 0.002), more often had mastectomy and less often had adjuvant radiation (p<0.001) than YW (n = 946). There were no differences in nodal or receptor status.

OW vs. YW were less likely to receive chemotherapy (28.1 vs. 81.3%, p<0.001); odds decreased with increasing age (OR 15.9 and 7.4 for women age 50-59 and 60-69 vs. ≥70, p<0.001). Odds of receiving chemotherapy were higher in women with HER2+, ER/PR negative tumours than those with HER2+, ER/PR positive (OR 2.2) and TN tumours (OR 1.7) (p = 0.004). Some factors associated with chemotherapy use differed between YW and OW: tumour size (T2 vs. T1, OR 2.6, p = 0.059) and grade (high grade vs. low grade, OR 6.5, p = 0.02) were only associated with chemotherapy use in YW. OW with more comorbid conditions (CCI≥2) were less likely to receive chemotherapy than those with zero or one comorbid condition (OR 5.0 and 2.7 respectively, p = 0.009).

In OW, reasons cited for not administering chemotherapy included: patient refusal (45.2%), patient age (38.1%), perceived minimal benefit (36.7%), patient comorbidity (28.6%), and concern about chemotherapy toxicity (28.6%). Chemotherapy was not mentioned in almost 1 in 5 cases (17.6%).

OW had worse 5-year RFS (75.4 vs. 83.2%, p = 0.002), BCSS (79.5 vs. 88.1%, p<0.001) and OS (63.7 vs. 85.8%, p<0.001). After adjusting for known prognostic factors and treatment differences, increasing age was still significantly associated with poorer 5-year OS (HR 1.2, p = 0.003), but not with BCSS after adjusting for the competing risk of non-BC deaths. 5-year OS, but not BC-specific outcomes (RFS, BCSS), was significantly better in those who received chemotherapy compared to those who did not.

Conclusion: OW with HER2+/TN BC are less likely to receive adjuvant chemotherapy than YW. Factors associated with chemotherapy receipt differ in OW, with tumor size and grade only being influential in YW. Age was only independently associated with OS and not BCSS, suggesting inferior BCSS rates in OW may be due to the presence of larger tumors or differences in treatments received by OW.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-09-04.

Abstract P6-06-04: Breast cancer in young women: Have the prognostic and predictive implications of breast cancer subtypes changed over time?

Background:

Breast cancer (BC) occurring in very young women has a worse prognosis compared to older women, and is the leading cause of cancer death in women aged < 40 years. Over the last decade BC management has evolved to incorporate increased understanding of BC subtypes and new therapeutic agents such as taxanes and trastuzumab. Whether the previously observed poor prognosis associated with BC in young women persists in the context of modern adjuvant therapies and relative to the BC subtypes has not been widely investigated.

Methods:

We analyzed BC outcomes of young (40-49 years) and very young (<40 years) patients (pts) according to subtype defined by immune histochemistry (IHC) and evaluated for any changes over time by comparing 2 cohorts representative of different time periods. Data from 1,101 women aged < 50 diagnosed with invasive BC between 1986-1992, and 1,945 women diagnosed between 2004-2007 were abstracted from the British Columbia Cancer Agency's Breast Cancer Outcomes Database and analyzed according to two age categories (40 years and 40-49 years) and subtype (IHC was available on the earlier cohort from an established tumor repository for those years). Subtypes were defined as follows: Luminal: estrogen receptor (ER) and/or progesterone receptor (PR) positive, and HER2 negative, HER2: HER2 positive and any ER/PR, and Triple Negative (TN) (ie for ER,PR and HER2 negative). Survival analysis was performed using the Kaplan Meier method.

Results:

Median follow-up was 13.2 years and 6.2 years for the 1986-1992 and 2004-2007 cohorts respectively. Within both time cohorts, luminal subtype pts <40 demonstrated worse survival compared with those 40-49. This difference remained after accounting for grade in the contemporary cohort alone (Hazard ratio 0.50 p = 0.0001). Inferior survival was observed for pts <40 with HER2 BC in the 1986-1992 cohort, no impact of age was demonstrated in the HER2 2004-2007 cohort. No survival difference was seen between the age groups for TN BC in either time cohort. Across the HER2 and TN subtypes, and for luminal pts 40-49 a significant improvement was seen in 5-year RFS and OS between the 2 time cohorts. 5-year RFS but not OS improved over time for the luminal pts <40.

5 year overall survival  1986-1992  2004-2007   5-yr OS (%)  5-yr OS (%) p value  (95% CI)  (95% CI)  Luminalage < 4082 (76-89)  88 (84-93) 0.138 age 40-4990 (87-92)  95 (94-97) 0.001 p value0.055  <0.001          HER2age < 4049 (35-63)  89 (83-95) <0.001 age 40-4966 (57-75)  89 (83-94) <0.001 p value0.017  0.879          TNage < 40 (101)67 (58-77)  82 (73-90) 0.011 age 40-49 (182)74 (67-80)  84 (79-89) <0.001 p value0.909  0.759  

Conclusions:

We observed a significant improvement in survival over time for both HER2 and TN BC which may reflect improvements in adjuvant strategies based on subtype presentation. Inferior survival for pts <40 with luminal BC persists in the modern era and this group should be targeted for research.

5 year relapse free survival  1986-1992  2004-2007    5-yr RFS (%)  5-yr RFS (%) p value  (95% CI)  (95% CI)  Luminalage<4065(57-74)  79 (74-85) <0.001 age 40-4977 (72-80)  92 (91-94) <0.001 p value0.009  <0.001          HER2age<4039 (25-52)  81 (70-92) <0.001 age 40-4958 (48-67)  84 (80-88) <0.001 p value0.039  0.879          TNage<4060 (51-70)  78 (69-87) 0.014 age 40-4963 (56-70)  77 (71-82) 0.001 p value0.868  0.933  

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-06-04.

Abstract P1-13-01: Risk of recurrence following 5 years of adjuvant hormone therapy for hormone receptor positive early breast cancer

Background

Introduction

The MA.17 study and combined analysis of the ATLAS and aTTom studies provide evidence of DFS and modest OS benefit from 10 years of hormone therapy (HT) for hormone receptor positive early breast cancer. The benefit may be less for women diagnosed today, due to advances in chemotherapy, initial HT, and radiation therapy since the era when these trials were conducted. Side effects accrue to all users of longer HT while benefit is experienced only by those who avoid recurrence, which is related to the baseline prognostic factors such as stage, grade, and disease biology.

Methods

To enhance informed patient-physician discussions, starting with a cohort of 10815 stage I-III hormone receptor breast cancer diagnoses between 1989 and 2004, we examined event-free survival (EFS) in years 5 to 10 among 1,061 premenopausal (<45 years at diagnosis) and 6,615 menopausal (≥50 years at diagnosis) women without documented relapse, CLBC, or death within the first 5 years. All patients were referred to the BC Cancer Agency (BCCA) with newly diagnosed disease, and all patients had adjuvant HT. EFS was defined as freedom from recurrence, from CLBC, or from breast cancer death without prior documented recurrence.

Results

Median follow up for the 7676 patients is 11 years. Event rates (including CLBC) in the second 5 years from diagnosis for stage I, II and III cancers were 6%, 12%, 23% for the pre-menopausal cohort, and 5%, 14%, 26% for the post-menopausal cohort. EFS in years 5-10 varied significantly by grade as shown below:

EFS years 5-10 after ER+ early Breast CancerStage, gradeAge 45 and younger at diagnosisAge 50 and older at diagnosis NEvents% EFS years 5-10 (95% CI)NEvents% EFS years 5-10 (95% CI)I, grade 1110698.2 (92.9,99.5)10375795.4 (93.7,96.6)I, grade 21741692.1 (86.7,95.3)133811194.6 (93.1,95.7)I, grade 368593.4 (83.2,97.5)3642994.8 (91.8,96.8)II, grade 174889.6 (78.0,95.3)6056193.0 (90.5,94.9)II, grade 22905186.3 (81.6,89.9)177330786.6 (84.8,88.2)II, grade 32103090.4 (85.4,93.8)82318781.9 (78.9,84.5)III, grade 160100531175.6 (59.6,86.0)III, grade 2591574.3 (60.6,84.1)2526774.3 (67.8,79.8)III, grade 3521178.0 (62.1, 87.9)1504072.0 (62.8,79.3)CI, confidence Intervals

Recurrences (excluding CLBC) after 10 years was 2% for the 10815 cases (representing 12% of all recurrences).

Conclusion

These data suggest that pre and postmenopausal women with stage I cancers of any grade, and postmenopausal women with stage II grade 1 cancers who have not experienced a relapse in the first five years can expect a less than 10% risk of recurrence, breast cancer death, or CLBC without further HT over the next 5 years. Prolonged HT in the identified groups may result in higher probability of harm than benefit and may best be avoided, although long term data will be needed to fully inform this risk benefit analysis.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-13-01.

Abstract P6-06-05: RadiotypeDx: Identification and validation of a radiation sensitivity signature in human breast cancer

Purpose: An unmet clinical need in breast cancer (BC) management is the identification of which patients will respond to radiation therapy (RT). We hypothesized that the integration of post-RT clonogenic survival data with gene expression data across a large spectrum of BC cell lines would generate a BC-specific RT sensitivity signature predictive for RT response in BC patients and allow identification of patients with tumors refractive to conventional therapy.

Methods: Using clonogenic survival assays, we identified the range of surviving fraction (SF) after 2 Gy of RT across 21 BC cell lines. Using SF as a continuous variable, the RT sensitivity score (RSS) was correlated to gene expression using a Spearman correlation method on an individual gene basis. Genes were selected for the signature based on positive or negative correlation with a p-value <0.05 and FDR of <0.01. Unsupervised hierarchical clustering identified differences in gene expression across resistant and sensitive cell lines to generate a radiation sensitivity (RS) signature. This signature was trained and validated in a separate human breast tumor dataset (185 pts) containing early stage, node-negative patients treated with surgery and RT alone without adjuvant chemotherapy to assess the predictive effect of RS signature on recurrence risk after RT. Gene function and potentially actionable targets from the signature were validated using clongenic survival and DNA damage assays.

Results: Clonogenic survival identifies a range of radiation sensitivity in human BCC lines (SF 77%-17%) with no significant correlation (r value <0.3) to the intrinsic BC subtype. Using Spearmans correlation method, a total of 126 genes were identified as being associated with radiation sensitivity (72 positively correlated, 54 negatively correlated). Unsupervised hierarchical expression discriminates gene expression patterns in the RT resistant and RT sensitive cell lines and is enriched for genes involved in cell cycle arrest and DNA damage response (enrichment p-value 5.0 E-22). Knockdown of genes associated with the radioresistance signature identifies previously unreported radiation resistance genes, including TACC1 and RND3 with enhancement ratios of 1.25 and 1.37 in BCC lines. Application of this RS signature to an independent breast cancer dataset with clinical outcomes validates the signature and accurately identifies patients with decreased rates of recurrence compared to patients with high expression of the radioresistant signature (p-value <0.0001, misclassification error rate .31, 12/13 patients with locoregional recurrence accurately identified).

Conclusion: In this study, we derive a human BC-specific RT sensitivity signature (RadiotypeDx) with biologic relevance from preclinical studies and validate this signature for prediction of recurrence in an independent clinical dataset. The signature is not correlated to the intrinsic subtypes of human breast cancer and thus provides useful information beyond traditional breast cancer subtyping. By identifying patients with tumors refractory to standard RT, this signature has the potential to allow for personalization of radiotherapy, particularly in patients for whom treatment intensification is needed.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-06-05.

Abstract P3-12-05: The BC provincial experience on FEC-D vs. AC-taxane protocol as adjuvant treatment for breast cancer

Background: Despite no direct prospective comparison, FECD and AC-Taxane (ACT) combinations are usually considered equally effective treatment options for early breast cancer. We evaluated the outcomes of patients (pts) in the BCCA database treated with FECD or ACT adjuvant chemotherapy between Jan/06 and Dec/11.

Methods: Female pts with a diagnosis of stage I-III breast cancer were eligible. The primary end-point was RFS (defined as freedom from local, regional or distant recurrence, or breast cancer death without documented recurrence). Secondary end-points were OS, number of cycles, chemotherapy delays, dose reductions, change in chemo protocol, and toxicity profile.

Results: 2013 pts were included: 1137 in the ACT and 876 in the FECD arm. Mean age was 52 (24-79). Baseline characteristics for ACT and FECD were, respectively: ductal histology in 95.5% vs 89.1% and lobular histology in 4% vs 10.6%; tumor size of 0.1-2.0 cm in 37 vs 34%, 2.1-5.0 cm in 50 vs 56% and ≥ 5.1 cm in 11 vs 9%; number of involved nodes were 0 in 42 vs 7%, 1-3 in 32 vs 65%, 4-9 in 16 vs 22% and ≥ 10 in 8 vs 6%; grade 1 in 2% vs 10%, grade 2 in 23% vs 40% and grade 3 in 74% vs 50%; ER/PR positive (+) in 21 vs 85%; ER/PR+/HER2+ in 40 vs 2%, ER/PR negative/HER2+ in 19 vs <1%, and triple negative in 18 vs 11%; local therapy consisted of breast conserving surgery (BCS) in 4 vs 1%, BCS + radiation (RT) in 42 vs 41%, mastectomy (Mx) in 16 vs 6%, Mx + RT in 36 vs 51%, and RT only to 1.5 vs < 1%. ACT and FECD arms showed a 5-year RFS of 84.3% vs 88.2%, and a 5-year OS of 88.2% vs 91.1%, respectively. After adjusting for tumor size, nodal involvement, histology, and LVI, pts in the ACT arm had a higher risk of relapse (HR = 2.269; 95% CI 1.528-3.368), and worse overall survival (HR = 1.796; 95% CI 1.128-2.857) than pts on FECD arm. A total of 815 cases have been reviewed to date for toxicity and chemotherapy delivery. In the ACT (415 pts) and FECD (400 pts) arms, respectively, 96.6% and 98.5% pts received the total number of planned anthracycline cycles, while 91.6% and 88.5% received the total number of planned taxane cycles. There was a dose delay in 36% and 40% of pts, a dose reduction in 30% and 41% of pts, and a change in protocol in 3% and 7% of pts in the ACT and FECD arms, respectively. Chemotherapy-related toxicity events leading to delay, dose reduction and change in protocol occurred in 119 (28.7%) and 216 (54%) pts in the ACT and FECD arms (p 0.01). The number of specific events for the ACT and FECD arms were, respectively: 15 (3.6%) vs 68 (17%) cases of febrile neutropenia, 11 (2.7%) vs 22 (5.5%) cases of grade 3 neutropenia, 46 (11.1%) vs 10 (2.5%) cases of neuropathy, 8 (1.9%) vs 33 (8.3%) cases of mucositis, and 5 (1.2%) vs 2 (0.5%) cases of cardiac toxicity.

Conclusions: Characteristics between arms were imbalanced due to the retrospective nature of the study. After adjustment for risk factors, relapse free and overall survival outcomes were better for the FECD arm. However, FECD had a worse toxicity profile, with a higher rate of life threatening events. The survival benefit was small, and it is possible that uncontrolled differences in prognostic factors that affected the choice for the ACT regimen may have lead to these findings, rather than inferiority of the ACT protocol itself.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-12-05.

Abstract P6-04-04: Maternal embryonic leucine zipper kinase (MELK) is a novel radiosensitizing and therapeutic target and is independently prognostic in triple-negative breast cancer

Background: While effective targeted therapies exist for estrogen receptor (ER)-positive and HER2/neu-positive breast cancer, no such effective therapies exist for ER-negative, PR-negative, and HER2-negative (“triple negative”) cancers. Given the lack of targeted agents for triple negative (TN) disease and their relative radiation insensitivity, it is clear that additional targets for treatment are critically needed.

Our previous work identified one such novel molecular target as maternal embryonic leucine zipper kinase (MELK), and we sought to investigate the impact of MELK expression on radiation response and patient outcomes.

Methods: Using gene expression arrays, we interrogated the expression of MELK in 2,061 breast tumor samples as well as a panel of 51 breast cancer cell lines. We measured protein expression in TN cancers with western blotting and used clonogenic survival assays to quantitate radiosensitivity of BCC lines at baseline and after MELK inhibition. Multiple datasets were used to evaluate the prognostic import of MELK. Kaplan-Meier analysis using local control and survival data was performed. Chi squared scores were calculated to determine significance and hazard ratios (HR) and 95% confidence intervals (CI) were calculated. A Cox proportional hazards model was constructed to identify potential factors of survival.

Results: We demonstrate that MELK expression is significantly elevated in human TN breast cancers, including chemoradiation resistant tumors (305 tumors compared to 1756 non-TN breast tumors; p-value 7.5 e-21). MELK protein and RNA expression is induced by ionizing radiation (5.6-7.5 fold at 72 hours, p-value <0.01). We characterized the radiation sensitivity of BCC lines and demonstrated that MELK expression is significantly correlated with radioresistance (as measured by clonogenic survival) in 21 breast cancer cell lines (R: 0.62, p-value 0.003). Inhibition of MELK using both siRNA and small molecule inhibitors induces radiation sensitivity in vitro with and enhancement ratio (ER) of 1.5-1.6. We demonstrate that high MELK expression is strongly correlated with p53 mutation positive status (p-value <0.001). Finally, local control and survival analyses of patients with BC showed that those patients whose tumors have high expression of MELK have significantly higher rates of LR after radiation and an overall poorer prognosis than patients with low expression of MELK (HR for LR 1.89-2.23, p-value 0.001; HR for overall survival 1.46-3.3; p-value <0.001 in 3 independent datasets). In multivariate analysis of all patients, only MELK expression and grade were significantly associated with worse local recurrence free (LRF) survival with a HR of 1.35 (95% CI 1.05-1.72, p-value < 0.01).

Conclusion: Here, we identify MELK as a potential biomarker of radioresistance and target for radiosensitization in triple negative breast cancers. MELK overexpression was associated with local failure across multiple data sets. MVA identified MELK as the strongest factor associated with poor local control. Our results support the rationale for developing clinical strategies to inhibit MELK as a novel target in triple-negative breast cancer.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-04-04.

Panitumumab monotherapy compared with cetuximab and irinotecan combination therapy in patients with previously treated KRAS wild-type metastatic colorectal cancer

BACKGROUND

The survival benefit for single-agent anti-epidermal growth factor receptor (egfr) therapy compared with combination therapy with irinotecan in KRAS wildtype (wt) metastatic colorectal cancer (mcrc) patients in the third-line treatment setting is not known. The objective of the present study was to describe the characteristics of, and to compare survival outcomes in, two cohorts of patients treated with either singleagent panitumumab or combination therapy with cetuximab and irinotecan.

METHODS

The study enrolled patients with KRAS wt mcrc previously treated with both irinotecan and oxaliplatin who had received either panitumumab or combination cetuximab-irinotecan before April 1, 2011, at the BC Cancer Agency (bcca). Patients were excluded if they had received anti-egfr agents in earlier lines of therapy. Data were prospectively collected, except for performance status (ps), which was determined by chart review. Information about systemic therapy was extracted from the bcca Pharmacy Database.

RESULTS

Of 178 eligible patients, 141 received panitumumab, and 37 received cetuximab-irinotecan. Compared with patients treated with cetuximab-irinotecan, panitumumab-treated patients were significantly older and more likely to have an Eastern Cooperative Oncology Group (ecog) ps of 2 or 3 (27.7% vs. 2.7%, p = 0.001). Other baseline prognostic variables and prior and subsequent therapies were similar. Median overall survival was 7.7 months for the panitumumab group and 8.3 months for the cetuximab-irinotecan group. Multivariate analysis demonstrated that survival outcomes were similar regardless of the therapy selected (hazard ratio: 1.28; p = 0.34). An ecog ps of 2 or 3 compared with 0 or 1 was the only significant prognostic factor in this treatment setting (hazard ratio: 3.37; p < 0.01).

CONCLUSIONS

Single-agent panitumumab and cetuximab-irinotecan are both reasonable third-line treatment options, with similar outcomes, for patients with chemoresistant mcrc.

A Survey of Phytophthora spp. in Midwest Nurseries, Greenhouses, and Landscapes

A survey of nurseries, greenhouses, and landscapes was conducted from 2006 to 2008 in order to determine the prevalence and diversity of Phytophthora spp. From sites in Iowa, Michigan, Ohio, and, predominantly, Indiana, 121 Phytophthora isolates were obtained from 1,657 host samples spanning 32 host genera. Based on sequence of the internal transcribed spacer (ITS) region of the ribosomal DNA, 11 Phytophthora spp. and two hybrid species were identified. A majority of the isolates were P. citricola (35.9%) or P. citrophthora (27.4%). Six isolates were confirmed as hybrids (four of P. cactorum × hedraiandra and two of P. nicotianae × cactorum) by cloning and sequencing the ITS region. Three P. cactorum × hedraiandra isolates were obtained from the same site, from three Rhododendron spp., which are known hosts to the parental species. The fourth isolate, however, was recovered out of a different location in a Dicentra sp., which is not a known host to either parental species, suggesting an expansion of host range of the hybrid isolate as compared with either parental species.

Abstract P4-16-02: A survival benefit from locoregional radiotherapy for node-positive and CMF treated breast cancer is most significant in Luminal A tumors

Background: Between 1978–1986, 318 premenopausal women treated with mastectomy for lymph node positive breast cancer, were randomized to CMF chemotherapy alone vs. CMF chemotherapy and adjuvant radiotherapy (RT) to the chest wall and regional lymph nodes. After 15 years of follow-up, post-mastectomy RT was associated with a statistically significant 29% relative risk reduction in mortality. Recent evidence suggests that Luminal A tumors, identified using hormone receptors and Ki67, have a particularly favorable prognosis. We retrospectively identified the Luminal A tumors from this clinical trial cohort to determine if the response to postmastectomy RT differed among Luminal A and non-Luminal A tumors.

Methods: 203 archival breast tumor samples from this study were used to construct a tissue microarray. Luminal A tumors were identified using an immunopanel consisting of: estrogen receptor, progestorone receptor, Her2, and Ki67. Luminal A tumors were defined as either ER or PR positive, Her2 negative, and Ki67 &lt; 14%. Kaplan-Meier estimates and the log-rank test were used to test the differences in locoregional relapse free survival (LRFS) and breast cancer specific survival (BCSS). Interaction between treatment and Luminal A/Non-luminal A were tested using Cox regression analysis.

Results: The intrinsic subtype was successfully determined in 144 breast tumors, and 49 were classified as Luminal A (34%). Survival outcomes at 10 years are summarized in Table 1:

Abstract P4-16-01: Accelerated hypofractionated whole breast radiotherapy for localized breast cancer: the effect of a boost on patient reported long-term cosmetic outcome

PURPOSE: Equivalent long-term local control and cosmetic outcomes between conventional and accelerated, hypofractionated whole breast radiotherapy (AWBRT) for early-stage breast cancer have been demonstrated. However, there is uncertainty about the long-term cosmetic outcome of a boost to the tumor bed following AWBRT (AWBRT+B). The primary outcome of this study was to evaluate the cosmetic effect of a boost using a patient reported questionnaire. The cosmetic subscale in the questionnaire was used to compare the appearance of the treated versus non treated breast between the boost and non-boost groups.

MATERIALS AND METHODS: Between 2000 and 2005, 4392 women 75 years and under with unilateral early-stage breast cancer received AWBRT alone or AWBRT+B. Random samples of 800 women treated with AWBRT alone and 800 women treated with AWBRT+B were identified from the 3960 women still alive at least 5 years after treatment without contralateral disease. The women were contacted by mail to complete a questionnaire based on the Breast Cancer Treatment Outcomes Scale (22 questions regarding cosmetic, pain and functional outcomes). Cochrane-Armitage (CA) trend test and Wilcoxon Rank-sum (WR) were used to compare baseline patient and treatment variables to long-term cosmetic outcomes between the two treatment groups.

RESULTS: 312 women (154 received AWBRT alone and 158 received AWBRT+B) completed the questionnaire. The median (range) age of respondents was 57 (40–75) years in the AWBRT alone group and 52 (32–75) years in the AWBRT+B group (p &lt; 0.001). The median (range) follow-up time after radiotherapy treatment was 8.7 (5.5–11.5) years in the AWBRT alone group and 7.8 (5.5–11.5) years in the AWBRT+B group (p &lt; 0.001). Boost doses ranged between 7.5 Gy in 3 fractions to 16 Gy in 8 fractions. The most commonly used boost regimen was 10 Gy in 4 fractions (70% of respondents). Women treated with AWBRT+B also had higher T stage, higher grade, were more likely to have had chemotherapy and trended towards having an increased number of positive nodes compared to the AWBRT alone group. Current weight, ER status, and use of hormonal therapy were similar between both groups.

When comparing the overall appearance of the treated to untreated breast, there was no significant difference between the women who received AWBRT alone and those who received AWBRT+B (42% stating no or slight difference vs. 41%) (p = 0.87 CA). Focusing on the cosmetic subscale in the questionnaire, the average summed score for the AWBRT alone group was slightly worse to the score for the AWBRT+B group (2.3 vs. 2.1, p = 0.02 WR). On the functional subscale, the average summed score for the AWBRT alone group was worse than the AWBRT+B group (1.8 versus 1.5, p &lt; 0.001 WR). On the pain subscale, the average summed score for the AWBRT alone group was better than the AWBRT+B group (1.6 versus 2.0, p &lt; 0.0001 WR). However, when the pain subscale was only applied to the area around the scar, the two groups were similar (2.0 for AWBRT alone and 2.0 for AWBRT+B, p = 0.71).

CONCLUSION: Similar to conventionally fractionated WBRT, patients who receive a boost after AWBRT self-report long-term slightly worse cosmetic and pain outcomes compared AWBRT alone.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-16-01.

Abstract P4-16-04: Outcome of stage II/III breast cancer treated with neoadjuvant versus adjuvant radiotherapy in British Columbia

Backgroud: Neoadjuvant radiotherapy (NRT) is generally recommended after systemic therapy for inoperable stage III breast cancer. At the BCCA, neoadjuvant radiation is also frequently offered for patients with operable node positive disease after neoadjuvant chemotherapy. There is a lack of randomised trial data comparing outcomes in stage II/III breast cancer when radiation therapy is delivered neoadjuvantly versus adjuvantly.

Aim: The primary objective of this study is to assess the clinical outcomes, as measured by relapse-free survival (RFS), overall survival (OS), and breast cancer-specific survival (BCSS), of women with stage II/III breast cancer treated with neoadjuvant chemotherapy and either neoadjuvant or adjuvant radiotherapy.

Methods: Patients were identified by linking the Breast Cancer Outcomes Unit (BCOU) with the British Columbia Cancer Agency Pharmacy data repository. Inclusion criteria included: Female, referred to BCCA with newly diagnosed disease, clinical stage II or III breast cancer, neoadjuvant chemotherapy, breast surgery performed as part of the initial treatment plan, RT (given adjuvantly or neo-adjuvantly to the breast/chest wall +/− regional nodes). Patients were excluded if they had a previous or synchronous in situ or invasive breast cancer. Demographic data, treatment characteristics, ER, PR and HER-2 status (when available) were extracted. Data was analyzed using descriptive statistics and Kaplan Méier curves survival analyses were produced using SPSS, V. 14.

Results: Between Jan 1, 1995 and Dec 31, 2008, 687 patients with stage II/III disease were identified. 394 patients received neo-adjuvant and 293 patients received adjuvant radiation. Patients treated with neoadjuvant vs. adjuvant RT differed in age (median: 51yrs vs. 49yrs, p &lt; 0.001), margin status (86.5% negative/5.1% positive/ 8.4% unknown vs. 94.2% negative/1.7% positive/4.1% unknown, p = 0.02), surgery (94.2% vs. 87.7% mastectomy, p = 0.003), and type of chemotherapy (50.3% vs. 24.6% anthracycline only, p &lt; 0.001) respectively. No differences in 5-year RFS (60.0 vs. 64.8 %, respectively, p = 0.07), 5 year BCSS (67.9 vs. 73.1 %, respectively p = 0.17) and 5-year OS (66.2 vs. 72.5 %, respectively, p = 0.06) were seen in the neoadjuvant vs. adjuvant population.

P3-14-09: A Phase II Preoperative Study of Dasatinib, a Multi-Targeted Tyrosine Kinase Inhibitor, in Locally Advanced “Triple-Negative” Breast Cancer Patients

Background: We previously reported that kinases (Src, Yes-1, cKIT, Abl, and EPH4) were druggable in triple negative breast cancer (TNBC). In this clinical trial, we sought to translate these findings by treating TNBC patients with dasatinib, a multi-targeted kinase inhibitor against these targets.

Methods: Women with stage II-III TNBC were eligible. Patients received dasatinib at 100 mg daily for 3 to 4 weeks before standard-of-care definitive surgery and chemotherapy. Biopsies were performed at baseline, week 1, and at the time of surgery. A cohort of patients had positron emission mammography (PEM; baseline and at 2–3 weeks of dasatinib therapy). This study was designed to detect an increase in clinical response rate from 10% to 25%, using a Simon optimal two stage design, with one-sided alpha=5% and power=80%. At least 3 responses out of 22 patients were needed to proceed to the second stage.

Results: 22 patients were enrolled (Table 1). Median tumor size was 7.0 cm (range 2.4-25 cm). Adverse events were modest, mainly grade 1–2 (headache: 45%, abnormal LFTs: 55%, GI: 23%, fatigue: 18%). One patient had a myocardial infarction 24 hours after starting dasatinib. Out of 22 patients, 2 (9%) had a clinical partial response after 3–4 weeks of therapy, 15 had stable disease (68%), while 5 had progressive disease (23%). Of the 8 patients who received paired PEM imaging, metabolic responses were observed in 2 patients (25%). Conclusion: A short course of dasatinib led to clinical responses in 2 out of 22 patients with TNBC, and the study did not proceed to second stage. Since TNBC is a heterogeneous disease, biomarker studies including sequencing of candidate genes like B-RAF for inactivating mutations might enable selection of those TNBC patients who could benefit from dasatinib.

P5-14-17: Stage IV at Presentation – Are HER2 Positive Tumors Overrepresented?

Background: A minority of patients are diagnosed with Stage IV breast cancer at presentation. Recent studies (Dawood 2010) have suggested a better outcome for de novo vs. recurrent Stage IV but they did not account for the variation of molecular subtype. We questioned whether HER2 overexpressing tumors were over-represented in de novo Stage IV disease, and whether this impacted on survival compared to other subtypes. Further, if different subtypes are more likely to present with metastatic disease, then this factor may need to be considered when developing guidelines for staging. With such considerations in mind, the purpose of this study was to determine the breast cancer subtypes according to stage. The main hypothesis was that HER2 positive tumors would be more prevalent in stage IV presentations. Methods: Using the Breast Cancer Outcomes Unit database from the BC Cancer Agency (BCCA), patients referred to the BCCA with a new diagnosis of breast cancer between 2005 and 2010 were selected. Patients with a previous or synchronous contralateral breast cancer, male cases, and patients with referrals for reasons other than new disease were excluded. Four subtypes according to available markers were defined: ER+/HER2−, ER+/HER2+, ER-/HER2+, and ER-/HER2−.

Results: Using these criteria, 485 cases of de novo stage IV disease and 10,723 stages I — III cases were extracted. After excluding cases with missing data, our final cohort consisted of 10,186 stage I-III cases and 425 stage IV cases. Distribution by subtype is presented in the Table below.

Impact of internal mammary node inclusion in the radiation treatment volume on the outcomes of patients with breast cancer treated with locoregional radiation after six years of follow-up

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Background: There is ongoing controversy about radiotherapy (RT) to internal mammary nodes (IMNs). Proponents of IMN RT cite the survival benefit seen in postmastectomy RT trials that included IMNs. However, others point out that benefit cannot be definitively attributed to IMN inclusion, as other lymph node regions were included in the RT arms. The issue is important, as IMN RT potentially increases cardiac and respiratory morbidity.

Methods: 2,413 women referred to a provincial RT program with newly diagnosed node positive, or T3/4N0 non-M1 invasive breast cancer, treated with a complete course of locoregional RT from 2001 to 2006, were retrospectively identified in a provincial database. IMN RT inclusion versus exclusion was determined through review of patient charts and RT treatment plans. Breast cancer-specific survival (BCSS), relapse-free survival (RFS), and overall survival (OS) were compared between the two groups using univariate and multivariable analyses.

Results: Analyses were performed at a median follow-up of 6.2 years. 41.4% of the subjects received IMN RT. The 5-year BCSS for the IMN inclusion and exclusion group was 84.8% versus 82.9%, respectively (HR 0.93 [95% CI 0.76, 1.14]; p=.51); the 5-year RFS was 87.4% versus 86.9% (HR 0.993 [0.83, 1.19]; p=0.94); and the 5-year OS was 84.8% versus 82.9% (HR 0.84 [0.70, 1.01]; p=0.06). After controlling for potentially confounding variables, there was no significant difference in BCSS (HR 0.96 [0.78, 1.18], p=0.88), RFS (HR 1.02 [0.84, 1.22], p=0.87), or OS (HR 0.91 [0.76, 1.10]; p=0.35).

Conclusions: After a median follow-up of 6.2 years, this population-based study shows no benefit from including IMNs in the locoregional RT volume after adjusting for other prognostic and treatment variables.

Is breast-conserving therapy a safe option for patients with tumor multicentricity and multifocality?

BACKGROUND

We compared outcomes after breast-conserving therapy (BCT) and mastectomy in multicentric (MC)/multifocal (MF) versus unifocal breast cancer.

PATIENTS AND METHODS

Women with stage I-II disease were classified as having unifocal or MC/MF disease. MC/MF and other prognostic factors were compared using binary logistic regression analysis. Univariate and multivariate analyses (MVAs) for relapse were carried out using cumulative incidence curves and Fine and Gray regression models. For the BCT group, matched analysis was added.

RESULTS

Median follow-up was 7.9 years, 11 983 having BCT (unifocal: 11 683, MC/MF: 300) and 7771 having mastectomy (unifocal: 6884, MC/MF: 887). MC/MF patients treated with BCT were 50-69 years old, free of extensive ductal carcinoma in situ (DCIS), and had smaller tumors. The cumulative 10-year local recurrence rates among unifocal and MC/MF disease were 4.6% [95% confidence interval (CI) 4.1% to 5.0%] versus 5.5% (95% CI 2.6% to 9.9%) for the BCT group, P = 0.76 and 5.8% (95% CI 5.2% to 6.5%) versus 6.5% (95% CI 4.7% to 8.7%) for the mastectomy group, P = 0.77. MC/MF was not a significant factor for relapse or survival on MVA. In the matched analysis, relapse rates were similar in the unifocal and MC/MF groups, P = 0.60.

CONCLUSION

BCT is a reasonable option in selected MC/MF cases, particularly those women aged 50-69 years old with small (<1 cm) MF tumors and without an extensive DCIS component.