Patient Characteristics Associated with Use of Monoclonal Antibody Treatment in Women with Metastatic Breast Cancer: A Population-Based Analysis

Introduction: Monoclonal antibodies (MoATB) were FDA approved for the treatment of patients with breast cancer (BrCA) whose tumors over expressed the human epidermal growth factor receptor 2 (HER2) in 1998. We sought to determine if certain patient characteristics and co-morbidities influenced MoATB use in a population-based practice setting of elderly women with metastatic BrCA. Methods: We identified female Medicare beneficiaries aged 66+ years diagnosed with incident metastatic BrCA without prior history for any cancer between 1999 and 2005 in the Surveillance, Epidemiology and End Results cancer registries (SEER). Charlson Co-morbidity index (CCI) and separate conditions within the index were created using linked Medicare claims in the year prior to the BrCA diagnosis. We identified both oral and infused chemotherapy (CH) from the Medicare claims from 1999 to 2006. Patients were categorized into three groups: no CH, MoATB+/-CH, and CH w/out MoATB. We performed bivariate statistics to compare the patient characteristics and comorbidities between the three groups, and the treatments groups only. Results: There were 3,820 women with metastatic BrCA, mean age 77 (SD 7.3) years, 81% were white race, 29% were married and 91% lived in an urban setting. 67% of these women (n=2,562) received no CH, 26% received CH w/out MoATB (n=994) and 7% received MoATB+/-CH (n=264). Overall the CCI was lower for women receiving either treatment as compared to no chemotherapy and between treatment groups for the young old (66-75 years) but not those aged 80+ years. The prevalence of congestive heart failure (CHF) and cerebrovascular disease was significantly lower in women receiving MoATB +/-CH, as compared to only CH, and also lower in both compared to no CH (n=2,462). Few women presenting with COPD or dementia were likely to be treated with either CH and/or MoATB compared to No CH. Other co-morbidity conditions within the CCI were not statistically different between the groups or the cell numbers were too small to analyze. Conclusion: MoATB use in the treatment of metastatic breast cancer steadily increased from 5% in 1999 to 23% in 2004. Use in 2005 was slightly lower but will be recalculated once the 2007 claims are available. In 2008, FDA released a black box warning for trastuzumab, the most frequently prescribed MoATB for BrCA, regarding the potential for the development of cardiomyopathy. Our results suggest that co-morbidities in particular CHF and cerebrovascular disease may influence the decision to use MoATB. Further research is necessary to examine the relationship between co-morbidities and the use of MoATB in the treatment of metastatic breast cancer.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2057.

Taxane Treatment in Women with Incident Stage IV Breast Cancer

Introduction: The overall benefit of chemotherapy for late stage breast cancer treatment has been demonstrated in clinical trials and “real world” observational studies, but there is less data on chemotherapy use among older women. In addition, estrogen receptor status can influence treatment decisions. Our objective was to explore the clinical and demographic characteristics of women who received chemotherapy, particularly taxanes, in a large population-based cohort of older patients with incident stage IV breast cancer.Methods: Older women (age 66 and over) diagnosed with incident stage IV breast cancer from 1999 to 2005 were identified in the Surveillance, Epidemiology and End Results (SEER) cancer registries. Treatment-related data were linked from Medicare claims. We limited our analysis to ER negative (ER-) women with the assumption that these women would not be receiving tamoxifen as SEER data do not have complete information on receipt of tamoxifen. Receipt of chemotherapy was identified from claims files. Bivariate analyses were performed to compare clinical and demographic characteristics of those who received taxanes, other chemotherapy, or no chemotherapy.Results: Of 3,820 older women diagnosed with incident stage IV breast cancer, 1,518 women (40%) were identified as ER negative, of whom 247 (16%) were treated with taxanes, 312 (21%) with other chemotherapy, and the remainder received neither. Mean age was 78, 84% of the study cohort was white, 27% were married, and 91% lived in urban areas. Fifty four percent of women had HER2 assays performed. Women who received taxanes were substantially younger (Mean=74, SD=5.49) than those who did not (Mean=80, SD=7.79) and had fewer co-morbidities (measured by Charlson co-morbidity index) (bivariate [see above] p=0.0003) than any other group. Individuals who received taxanes were less likely to be married, receive radiation or undergo surgery. Only 8% of those treated with taxanes had 2 or more medical conditions compared to 18% of those receiving other chemotherapy and 74% of those with no chemotherapy. Treatment groups varied in regard to some medical conditions including CHF, cerebrovascular disease, and dementia. For example, only 8% of those receiving taxanes had CHF, compared to 13% among the 'other chemotherapy' group and 78% among those receiving no treatment (bivariate [see above] p=0.0003). A similar trend was revealed with the other medical conditions, with taxane users consistently presenting with lower prevalence for each condition. Interestingly, no one who had dementia received any chemotherapy.Conclusion: Findings from this descriptive study showed that age and co-morbidity were the most important factors associated with receipt of taxanes as well as of other chemotherapy. However, those who received taxanes were the youngest and evidenced the least comorbidity of the 2 groups. Further study is needed to help inform clinicians in making optimum treatment recommendations for their older female patients with incident advanced breast cancer.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2068.

Chemotherapy Treatment and Survival in Estrogen Receptor Negative Metastatic Breast Cancer: A Population-Based Analysis

Introduction: Although controlled clinical trials have demonstrated a beneficial effect of various chemotherapy regimens on survival in breast cancer (BC), little is known about treatment patterns and survival benefit in the “real world” population of elderly women with metastatic BC. Methods: We identified female Medicare beneficiaries aged ≥66 years with metastatic BC diagnosed from 1999 to 2005 in the Surveillance, Epidemiology and End Results cancer registries (SEER). Patients with a prior history of any cancer were excluded. Treatment-related data were abstracted from linked Medicare claims. Since Medicare claims have incomplete information on oral selective estrogen receptor modulators, we limited our study cohort to estrogen receptor negative (ER-) women. Chemotherapy was defined as the receipt of any chemotherapeutic regimen within 6 months after diagnosis. Initial regimens were characterized based on drugs given during the first 30 days of chemotherapy. We used a continuous-time interval-censored survival analysis to determine the effect of chemotherapy on hazard of any-cause death, controlling for sociodemographic and clinical factors, including proxy measures for performance status. Results: We identified 1518 ER(-) women diagnosed with metastatic BC in SEER. Mean age was 77.6 (SD 7.6) years, 84% were white race and 27% were married at the time of diagnosis. Of the 1518 metastatic ER(-) BC patients, 493 (32%) received chemotherapy. As compared to women who did not receive chemotherapy, women who received chemotherapy were more likely to be younger, married, have lower pre-cancer comorbidity as measured by the Charlson comorbidity index, have seen an oncology specialist and have cancer-directed surgery or radiation prior to chemotherapy. Initial regimens comprised predominantly one (31%) or two (46%) drug classes. The most common regimens were taxanes only (18%), anthracycline+alkylating agents (17%) and antimetabolite+alkylating agent (9%). Overall median followup time was 7 months; 1223 women (81%) died during followup. Median survival time was 5 months among women who did not receive chemotherapy and 15 months among women who received chemotherapy. Chemotherapy was associated with a statistically significant survival benefit (adjusted Hazard Ratio 0.61, 95% confidence interval 0.54, 0.70). Conclusion: In this population-based study of older women, there was a variety of chemotherapy regimens used for metastatic ER(-) BC. Chemotherapy received within 6 months after diagnosis was associated with a 39% reduction in hazard of death. These findings reflect chemotherapy use outside of the clinical trial setting and have important clinical and policy implications for the study of treatments among older women with advanced BC.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2064.

UV disinfection of wastewater effluents for unrestricted irrigation

Wastewater reuse in arid regions is important for the production of a water resource to be utilised for non-potable purposes and to prevent the environmental transmission of disease-causing agents. This study was conducted to evaluate the effect of water quality on the comparative disinfection efficiency of viruses, bacteria and spores by UV irradiation. Furthermore, the microbial quality of effluent produced by coagulation, high rate filtration (HRF) and either UV irradiation or chlorination was determined. Using low pressure collimated beam, a UV dose of 80 mWs/cm2 was needed to achieve a 3-log10 inactivation of either rotavirus SA-11 or coliphage MS2, whereas over 5-log10 inactivation of E. coli was reached with a dose of only 20 mWs/cm2. B. subtilis inactivation was found to be linear up to a dose of 40 mWs/cm2 and then a tailing up to a UV dose of 120 mWs/cm2 was observed. It is worth noting that effluent turbidity of < 5 NTU did not influence the inactivation efficiency of UV irradiation. Operation of a pilot plant to treat secondary effluent by coagulation, HRF and UV disinfection at a UV dose of 80 mWs/cm2 resulted in the production of high quality effluent in compliance with the Israel standards for unrestricted irrigation (< 10 CFU/100 mL faecal coliform and turbidity of < 5 NTU). Sulphite reducing clostridia (SRC) were found to be more resistant than coliphages and F coliform for UV irradiation. The results of this study indicated that UV disinfection is suitable for the production of effluents for unrestricted irrigation of food crops.