Trends in the Use of Hypofractionation in Treatment of Breast Cancer in Botswana

PURPOSE/OBJECTIVE(S)

Clinical trials have shown that moderate hypofractionation (HF) is clinically effective as adjuvant treatment to breast conserving surgery or following mastectomy with advanced disease. ASTRO issued updated guidelines in 2018, expanding the population eligible to receive HF to all patients, regardless of age and tumor stage. Use of HF can promote efficient resource utilization for over-burdened health care systems; however, global adoption of HF has been previously only reported via ESTRO survey of individual physicians. These data note that HF following lumpectomy is 40% in Africa vs. >90% in North America, with limited data on the uptake of HF within individual African countries. In this study, we characterize temporal trends and clinical, socio-demographic factors associated with the use of HF in breast cancer in Botswana.

MATERIALS/METHODS

We retrospectively analyzed a cohort of breast cancer patients receiving curative intent radiation between 2015 and 2022 at the only radiation clinic in Botswana. We compared patients' characteristics between those who received HF vs. standard fractionation (SF) and report chi-square statistics when appropriate. We fit a multilevel mixed-effects logistic regression model with a random intercept for district while adjusting for fixed effects such as HIV infection status, laterality, hormone receptor status, and marital status.

RESULTS

A total of 234 patients were prescribed curative intent radiation between 2015 and 2022 in Gaborone, Botswana. Median age at diagnosis was 51 years old, and the majority of patients presented with stage III disease (61.9%, 109/234). 26.9% of this population were women living with HIV (WLWH), and 71% lived >100km from the hospital. HF was utilized overall in 59.4% (139/234) of patients. Most common fractionation patterns included: 4005cGy/15fx and 4267cG/16fx. One patient received ultra-HF (2600cGy/5fx). In unadjusted chi-square analysis, a higher proportion of HF was seen in right vs left-sided breast cancer (65.8% vs. 50.9%, p = 0.02), increasing year of diagnosis from 2015 - 2022 (p<0.001), and among patients >/ = 40 years of age vs. those <40 years of age (62.8% vs 42.1%, p = 0.017). Temporal trends show a significant increase in the utilization of HF starting from 23.8% (5/21) in 2015, to 61.5% (32/52) in 2018, and finally 100% (11/11) of cases in 2022. Our regression analysis shows that there is no statistically significant between-district variance or patient-level factors that associate with the uptake of HF. The overall utilization rate for HF between 2015-2022 was 59.4% (95% CI: 53.0%-65.5%).

CONCLUSION

Based on recent survey results the uptake of HF among African countries is lower than that of North America. To our knowledge, this is the first quantitative analysis of the utilization of HF over 5 years in an African country. Further analysis on factors related to physician prescription of hypofractionation is warranted, including influence of breast laterality, age, and primary surgery type.

Impact of Chemotherapy Stock-Out on Standard Therapy Delivery Among Cancer Patients in Botswana

Background: Cancer drug shortages represent a complex global issue with potentially adverse survival outcomes. Up to 98% of oncologists and pharmacists surveyed in North America reported at least 1 drug shortage in the prior year and 66% reported at least one patient who had clinical care impacted by the shortage. In low- and middle-income countries (LMICs), these shortages are even more frequent. No studies to our knowledge have evaluated the impact of chemotherapy stock-out on receipt of standard cancer therapy in LMICs. Aim: Quantify the association between the duration of chemotherapy stock-out and the risk of having a suboptimal therapy delivery event, compared with standard delivery of therapy among cancer patients in Botswana. Methods: Prevalent cohort study of patients with cervical, breast, prostate, esophagus, Kaposi sarcoma, head and neck cancers, lung, uterine, ovarian and colorectal cancers who received any systemic therapy between 01/01/16-12/31/16 at Princess Marina Hospital, Botswana. Primary exposure was stock-out duration per cycle interval calculated by generating a code for the six different patterns for chemotherapy stock-out, using stock data at the Central Medical Stores. Primary outcome was suboptimal therapy delivery defined as a dose reduction, dose delay or switch in intended therapy. We measured statistical associations using two sample t-test and mixed effects univariate and multivariate logistic regression models. Results: 378 patients were identified who met diagnostic criteria and received systemic chemotherapy in 2016. Of these, 293 received commonly prescribed standard regimens who contributed 1452 cycle intervals and were included in our analysis. Majority of the patients (48%) had breast cancer. The mean duration of stock-out for receipt of standard therapy without events was 3.2 days (95% CI: 2.8-3.7) compared with 7.8 days for patients who had a suboptimal therapy delivery event (95% CI: 6.6-9) ( P < 0.0001). Male sex, age < 65 and HIV-positive status were also significantly associated with an increased risk of experiencing dose reduction, change in therapy or switch in therapy. Adjusting for these factors in a mixed effects logistic regression, each week of stock-out was independently associated with an 80% increased risk of having a suboptimal therapy delivery event (OR=1.8 (95% CI: 1.6-2.0, P < 0.0001)). Conclusion: Chemotherapy stock-out is independently associated with an 80% increased risk of a patient experiencing dose reduction, change in therapy or delay in therapy. The risk increases with longer duration of stock out. Given prior data showing that these events lead to worse survival outcomes, our further analysis is focusing on quantifying risk of stock-out on survival outcomes in this population. to determine whether interventions promoting standard therapy delivery are warranted to optimize survival outcomes.

LCIS and tamoxifen use: A single institution review

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Background: Results of the NSABP-P1 trial were published in 1998 showing a 50% reduction in breast cancer in the high- risk population with the use of tamoxifen. The use of tamoxifen is individualized, and depends on both patient and physician factors. We looked at the recommendations for and the use of tamoxifen in women with LCIS. Methods: A retrospective chart review at a single institution was performed from March 27, 1980 through September 19, 2005 for patients diagnosed with LCIS. Pathology and operative reports, as well as patient notes were reviewed for discussions about tamoxifen. Data was collected on whether a discussion took place, whether tamoxifen was or was not advised, whether the patient declined to take tamoxifen, whether they took it in the past or were currently on tamoxifen. We also examined the rate of DCIS and invasive cancer in this population. Results: There were 321 patients diagnosed with LCIS. Of those patients 193 were diagnosed after the publication of the P1 trial. Of these 193 patients we identified 104(54%) patients whose charts contained notes indicating a discussion about tamoxifen. The results of the discussion about tamoxifen are as follows: 21(20%) patients were currently taking tamoxifen, 16(15%) had taken it in the past, 37(36%) patients declined to take tamoxifen, and 17(16%) had not made a decision about taking tamoxifen. There were 13(13%) patients for whom tamoxifen was advised against. In the entire cohort of 321 patients, 15% went on to develop DCIS or invasive cancer in the first 12 years of follow up. We did not look at cancer rate Vs tamoxifen use due to the small numbers with available information. Conclusions: While the P1 trial recommends tamoxifen for breast cancer prevention in high-risk patients, in our experience, almost half of the patients did not have a documented discussion about the medication, and the majority of those who did decided not to take tamoxifen. This will likely have a large impact on the rate of DCIS and invasive breast cancer in this group.

No significant financial relationships to disclose.