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Context: Breast cancer is the most common cancer and the second leading cause of cancer death among US women. Compounding the impact of breast cancer are significant age and race differences that have been noted in the incidence and mortality of breast cancer. The elderly suffer disproportionately from the burden of breast cancer because they are a rapidly growing population in the US and they also have relatively higher mortality and morbidity from this disease. There is conclusive evidence of the efficacy of adjuvant systemic treatment in prolonging survival. However, very little is known about the frequency of use of this treatment in the elderly. On the other hand, racial differences in breast cancer reveal that although black women have lower incidence of breast cancer than whites, they sustain higher mortality rates. There is evidence that the reduced survival among blacks may be attributable more to differences in socioeconomic status and access to appropriate care, rather than to biological differences between the races. Therefore, it is apparent that the elderly and ethnic minority groups, especially black women, experience poorer outcomes from their breast cancers than their counterparts. Age and race disparities in treatment of early breast cancer may be one mechanism by which these women suffer poorer outcomes. Therefore, the overall goal of this dissertation was to examine age and race disparities in the treatment of early breast cancer as articulated in the three specific aims described below.
Specific Aims: The aims of this dissertation were to: (1) determine the frequency of use of adjuvant systemic treatment for early breast cancer among women 65 years of age and older, (2) examine whether differences exist in receipt of standard treatment for early breast cancer between black and white women, and (3) examine whether differences exist in delays in initiation of treatment for early breast cancer between black and white women.
Design, Setting, and Patients: Aim 1 utilized data from the population-based New Jersey Cancer Registry (NJSCR) to ascertain the frequency of use of adjuvant systemic treatment among 200 women (100 fatal cases and 100 non-fatal cases) who were ≥ 65 years of age and diagnosed with early stage breast cancer during 1987-1998. Study subjects were stratified based on their estrogen receptor (ER) status into ER positive and ER negative cases. NJSCR data provided information on patient and tumor characteristics as well as information on treatment received and their providers. Cancer registry data are usually obtained from hospital tumor registrars, while adjuvant systemic treatment is frequently administered on an outpatient basis. Therefore, cancer registry data was supplemented with data obtained from patients' primary care physicians and oncologists.
For Aims 2 and 3 of this dissertation, a retrospective cohort study was designed using a linked NJSCR and New Jersey Medicaid dataset for the years 1997 through 2001. Participants in these studies were women 20-64 years of age who were diagnosed with early-stage breast cancer (SEER Summary Stage 'localized' and 'regional spread to lymph nodes') between January 1997 and December 2001. Women who were neither white nor black, who were diagnosed with other cancers, and whose breast cancer was not the primary cancer were excluded. The linked database was used to obtain diagnostic, prognostic, and treatment information on 237 black and 485 white women.
Descriptive analyses were done to characterize the study populations for all three aims. For Aim 1, the frequency of use of surgical therapy, hormonal therapy alone, chemotherapy alone, and hormonal therapy in combination with chemotherapy was calculated separately for subjects with ER positive and ER negative tumors. Multivariate logistic regression models were constructed to examine the predictors of adjuvant hormonal and chemotherapy use. For Aim 2, logistic regression models were constructed to compare receipt of standard treatment between blacks and whites. Racial differences in breast cancer specific and overall survival were evaluated using Cox proportional hazard models. For Aim 3, we compared blacks and whites with respect to delays in initiation of surgical treatment after confirmed diagnosis, of adjuvant radiation therapy after breast conserving surgery, and of adjuvant hormonal and chemotherapy after definitive surgery. Logistic regression models were constructed to examine the association between delays in initiation of surgical treatment (≥1 month vs. <1 month), radiation treatment after breast conserving surgery (≥2 months vs. < 2 months), adjuvant hormonal therapy and chemotherapy (≥1 month vs. <1 month, ≥2 months vs. <2 months, and ≥3 months vs. <3 months) and race.
Results: Aim 1 of this dissertation showed that 28% of elderly New Jersey women with early breast cancer received chemotherapy alone or in combination with hormonal therapy whereas 42% received hormonal therapy alone. Only 40% of the women with ER negative tumors received chemotherapy alone or in combination with hormonal treatment and 30% of patients did not receive any adjuvant therapy. Examination of racial differences in receipt of standard treatment (Aim 2) revealed no differences in receipt of surgical, radiation, or adjuvant systemic treatment. Breast cancer specific mortality (Hazard ratio=1.37; 95% confidence interval = 0.94 -- 1.98) and all-cause mortality (Hazard Ratio=1.43; 95% confidence interval=1.08-1.89) were higher among blacks than whites. Although no racial differences were noted in receipt of standard treatment, Aim 3 showed that blacks as compared to whites more often experienced delays of 2 or more months and 3 or more months in initiation of adjuvant chemotherapy after definitive surgery. Also, delays of 2 or more months in adjuvant radiation therapy after breast conserving surgery were observed more frequently among blacks (76.7%) as compared to whites (63.0%). After controlling for other predictors, compared with white women, black women had 1.49-fold odds (95% confidence interval, 0.89, 2.50) of delay of 2 or more months and 1.90-fold odds (95% confidence interval, 0.92, 3.93) of delay of 3 or more months in adjuvant chemotherapy. Delays in adjuvant radiation and chemotherapy were also associated with poorer survival as compared to those who did not experience such delays. No racial differences were observed in delays in initiation of surgical treatment and adjuvant hormonal therapy.
Conclusion: The research in this dissertation confirmed that significant age and race disparities exist in the treatment of early breast cancer and factors underlying these disparities need to be studied further. Among elderly New Jersey women, almost 40% of women with ER positive tumors did not receive adjuvant hormonal therapy, while 60% of women with ER negative tumors did not receive adjuvant chemotherapy. The frequency of use of adjuvant systemic therapy in the elderly New Jersey population is significantly lower than that reported among middle aged women from other reports. Efforts in increasing the use of hormonal and adjuvant chemotherapy may help to reduce the excess mortality burden among elderly women with early breast cancer. The results from Aims 2 and 3 show that although receipt of standard treatment for early breast cancer was similar between black and white New Jersey Medicaid beneficiaries with early breast cancer, blacks experienced delays in initiation of adjuvant radiation and chemotherapy more often than their white counterparts. This implies that when socioeconomic status and access to care are similar between blacks and whites, receipt of standard treatment is also similar. In spite of this, blacks experience longer delays in treatment initiation suggesting that other factors may also play a role. Identifying the reasons for this difference requires a more in-depth look at the role of several patient, physician, and care-process level factors involved in the complex management of patients with breast cancer.

Ph.D.

Includes bibliographical references.

http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.17096

ETD_726

doi:10.7282/T3Z038JD

ETD doctoral

The author owns the copyright to this work.

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