Shortened radiation therapy schedules for early-stage breast cancer: a review of hypofractionated whole-breast irradiation and accelerated partial breast irradiation

Incidence of radiation-associated sarcoma after breast-conserving surgery plus radiation

BACKGROUND

Radiation-associated sarcoma (RAS) is a rare sequela of radiotherapy. Radiotherapy modalities for breast conservation and radiation treatment (BCT) have changed over time. We sought to determine if the incidence of RAS after BCT has changed over time.

METHODS

We identified breast cancer survivors (diagnosed 1988-2012) treated with BCT within the SEER database. We excluded patients with prior cancer, <1-year follow-up/survival, and nonexternal beam radiation (n = 276 301). We identified patients with a subsequent chest sarcoma diagnosis. The primary predictor variable was a 5-year period of breast cancer diagnosis year (1988-1992, 1993-1997, etc.). The incidence of sarcoma was estimated by the Kaplan-Meier method, censoring at sarcoma diagnosis, death, or last follow-up (available through December 2017). Given the known latency of RAS, we used Joinpoint analysis to identify the time point at which RAS incidence significantly increased (start of the analytic window). A log-rank test assessed differences in RAS incidence by diagnosis year.

RESULTS

The incidence of RAS was 0.03% at 5 years (95% confidence interval [CI]: 0.03-0.04) and 0.16% at 10 years (95% CI: 0.14-0.18). No statistical difference in RAS incidence by diagnosis year was observed (p = 0.2).

CONCLUSIONS

RAS remains a rare but persistent sequela after BCT. As new radiation modalities become more common, ongoing surveillance is necessary to track these rare events.

A comparison of timely completion of hypofractionated and traditional adjuvant radiation therapy in early-stage breast cancer: Evidence of impact on reducing racial and socioeconomic disparities

BACKGROUND

Timely completion of adjuvant radiation after breast conservation therapy is associated with decreased mortality and increased disease-free survival. Few data exist comparing timely completion between hypofractionated radiation and traditional radiation at a national level or across racial and socioeconomic cohorts.

METHODS

A retrospective review of the National Cancer Database (2012-2016) on patients undergoing breast conservation therapy for early-stage breast cancer, specifically T1 or T2, N0, M0 patients, was performed. Multivariable logistic regression models were used to compare timely completion of hypofractionated radiation (within 5 weeks of initiation) and traditional radiation (within 7 weeks) across patient, tumor, and facility characteristics.

RESULTS

In total, 210,816 patients met criteria, with 59.4% receiving traditional radiation (n = 125,140) and 40.6% receiving hypofractionated radiation (n = 85,676). Overall, 82.8% of patients achieved timely completion of radiation. Among hypofractionated radiation patients, 94.5% of patients achieved timely completion, whereas only 74.8% of traditional radiation patients achieved timely completion (P < .0001). Regarding race/ethnicity, all groups benefited substantially in timely completion of hypofractionated radiation over traditional radiation. However, both treatment cohorts demonstrated that Black (odds ratio (hypofractionated radiation) = 0.842, odds ratio (traditional radiation) = 0.821) and Hispanic (odds ratio (hypofractionated radiation) = 0.917, odds ratio (traditional radiation) = 0.907) patients had lower odds of timely completion compared to White patients (P < .0001). Lower high school graduation rate, median income for patients' ZIP code, and Medicaid were also associated with lower odds of timely completion for both hypofractionated radiation and traditional radiation (both P < .0001).

CONCLUSION

Timely completion of radiation therapy in breast conservation therapy is greater for patients receiving hypofractionated radiation than traditional radiation across racial and socioeconomic cohorts. Disparities in timely completion were substantially reduced with hypofractionated radiation utilization. However, there are treatment disparities across racial and socioeconomic cohorts that persist in both treatment groups.

Partial-breast irradiation versus whole-breast radiotherapy for early breast cancer: A systematic review and update meta-analysis

PURPOSE

The purpose of this study was to compare the treatment outcomes of partial-breast irradiation (PBI) versus whole-breast radiotherapy (WBRT) in early breast cancer.

METHODS AND MATERIALS

Eligible randomized clinical trials were identified on Medline, Embase, the Cochrane Library, and the proceedings of annual meetings through December 2019. A meta-analysis for local recurrence (LR), overall mortality (OM), and non-breast cancer mortality (NBCM) was conducted. When possible, the outcomes were calculated for 5, 7, and 10 years of followup. A subgroup analysis by PBI technique (brachytherapy [BT], external beam radiotherapy [EBRT], intraoperative radiotherapy [IORT], and mixed) was performed. A p value < 0.05 was considered significant.

RESULTS

Eleven randomized clinical trials with a total of 14,436 patients (7186 PBI vs. 7250 WBRT) were included in the meta-analysis. The odds ratio (OR) for LR in 5 y was 1.46 (95% CI 1.15-2, p = 0.024) for PBI. In the subgroup analysis, no significant difference for LR was observed between PBI and WBRT using BT (p = 0.51), EBRT (p = 0.25), or mixed techniques (p = 0.89). The only subgroup with statistical difference was IORT 3.1 (95% CI 1.2-7.6, p = 0.014). No significant difference in LR was observed with 7 and 10 years among the groups. The OM had no difference at 5, 7, and 10 years of followup for any subgroup. A nonsignificant difference was observed comparing PBI with WBRT for NBCM OR = 1.24 (95% CI 0.98-1.57, p = 0.07). The rates of cardiac death, contralateral breast cancer, and development of second tumor were not significant.

CONCLUSIONS

The LR with PBI is low and similar to WBRT in selected early breast cancer with a longer followup. The subgroup analysis detected a significant difference for LR associated with IORT and no significant difference for BT and EBRT. Our results confirm a nonsignificant difference for OM and NBCM between PBI and WBRT.

Could a Personalized Strategy Using Accelerated Partial Breast Irradiation be an Advantage for Elderly Patients? A Systematic Review of the Literature and Multidisciplinary Opinion

Introduction. Elderly patients are underrepresented from a majority of clinical trials and the choice of the best treatment becomes a challenge. The optimal treatment should be personalized and based on a multidisciplinary approach that includes radiation oncologists, surgeons, geriatricians, medical oncologists, social workers, and support services. The global evaluation of the patients and the creation of nomograms may facilitate the definition of long-term treatment benefits minimizing the use of unnecessary therapy. Material and Method. A systematic research using PubMed, Scopus, and Cochrane library was performed to identify full articles analyzing the efficacy of APBI in elderly patients with breast cancer. ClinicalTrials.gov was searched for ongoing or recently completed trials, and PROSPERO was searched for ongoing or recently completed systematic reviews.

Omission of postoperative radiation after breast conserving surgery: A progressive paradigm shift towards precision medicine

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Post-operative radiotherapy is standard after breast conservation in early breast cancer.

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To de-escalate the treatment burden, indentifying a subset at very low risk of relapse is crucial.

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Clinical and pathological factors are important, but can be integrated with genomic signatures.

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Ongoing trials will provide evidence on patients at low risk for radiotherapy omission.

Radiation therapy is a standard therapeutic option in the post-operative setting for early breast cancer patients after breast conserving surgery, providing a substantial benefit in reducing the risk of local relapse with a consequent survival gain. Nevertheless, the reduction in the burden related to treatment is becoming crucial in modern oncology for both local and systemic therapies and investigational efforts are being put forward by radiations oncologists to identify a subset of women at very low risk to be potentially omitted from post-operative irradiation after breast conservation. Clinical factors, classical pathological parameters and new predictive scores derived from gene expression and next generation sequencing techniques are being integrated in the quest toward a reliable low-risk profile for breast cancer patients. We herein provide a comprehensive overview on the topic.

Dosimetric evaluation and systematic review of radiation therapy techniques for early stage node-negative breast cancer treatment

Radiation therapy (RT) is essential in treating women with early stage breast cancer. Early stage node-negative breast cancer (ESNNBC) offers a good prognosis; hence, late effects of breast RT becomes increasingly important. Recent literature suggests a potential for an increase in cardiac and pulmonary events after RT. However, these studies have not taken into account the impact of newer and current RT techniques that are now available. Hence, this review aimed to evaluate the clinical evidence for each technique and determine the optimal radiation technique for ESNNBC treatment. Currently, six RT techniques are consistently used and studied: 1) prone positioning, 2) proton beam RT, 3) intensity-modulated RT, 4) breath-hold, 5) partial breast irradiation, and 6) intraoperative RT. These techniques show dosimetric promise. However, limited data on late cardiac and pulmonary events exist due to challenges in long-term follow-up. Moving forward, future studies are needed to validate the efficacy and clinical outcomes of these current techniques.

Efficacy and safety of accelerated partial breast irradiation: a meta-analysis of published randomized studies

Background and purpose

Accelerated partial breast irradiation (APBI) technology has theoretical advantages in comparison with traditional adjuvant radiation therapy (whole-breast irradiation; WBI) after breast-conserving surgery. However, published randomized controlled trials have shown inconsistent outcomes. Therefore, a comprehensive assessment of the effectiveness and safety of APBI technology is needed.

Results

A total of 7 studies of 7452 patients were included in this analysis. All 7 studies reported local recurrence as an outcome. Meta-analysis of 5 trials that included 6486 patients showed significantly different 5-year local recurrence rates for APBI and WBI groups (hazard ratio = 4.54, 95% confidence interval: 1.78–11.61, p = 0.002). Further analysis showed that this difference may be related to the choice of treatment methods. Benefit was conferred to the APBI group for the outcome of non-breast cancer deaths. There was no significant difference between the two groups in terms of nodal recurrence, systemic recurrence, overall survival, or mortality rates. Toxicity side effects and cosmetic effects were similar in both groups, but intraoperative radiotherapy seemed to have a greater acute response.

Material and methods

Searches for relevant randomized controlled trials of APBI versus WBI were performed using the following sources: PubMed, EMBASE, Cochrane Library, Web of Science. Two independent observers evaluated the identified studies. The meta-analysis was conducted using RevMan 5.2 software.

Conclusions

Although the analysis showed that patients receiving APBI had a higher local recurrence rate, subgroup analyses suggested that this might be related to treatment options. Patients who receive accurate radiotherapy may have greater benefits. APBI is a promising treatment technology and more phase III clinical trials are expected based on new treatments.

Nation-Scale Adoption of Shorter Breast Radiation Therapy Schedules Can Increase Survival in Resource Constrained Economies: Results From a Markov Chain Analysis

PURPOSE

Hypofractionated whole breast irradiation and accelerated partial breast irradiation (APBI) offer women options for shorter courses of breast radiation therapy. The impact of these shorter schedules on the breast cancer populations of emerging economies with limited radiation therapy resources is unknown. We hypothesized that adoption of these schedules would improve throughput in the system and, by allowing more women access to life-saving treatments, improve patient survival within the system.

METHODS AND MATERIALS

We designed a Markov chain model to simulate the different health states that a postlumpectomy or postmastectomy patient could enter over the course of a 20-year follow-up period. Transition rates between health states were adapted from published data on recurrence rates. We used primary data from a tertiary care hospital in Lahore, Pakistan, to populate the model with proportional use of mastectomy versus breast conservation and to estimate the proportion of patients suitable for APBI. Sensitivity analyses on the use of APBI and relative efficacy of APBI were conducted to study the impact on the population.

RESULTS

The shorter schedule resulted in more women alive and more women remaining without evidence of disease (NED) compared with the conventional schedule, with an absolute difference of about 4% and 7% at 15 years, respectively. Among women who had lumpectomies, the chance of remaining alive and with an intact breast was 62% in the hypofractionation model and 54% in the conventional fractionation model.

CONCLUSIONS

Increasing throughput in the system can result in improved survival, improved chances of remaining without evidence of disease, and improved chances of remaining alive with a breast. These findings are significant and suggest that adoption of hypofractionation in emerging economies is not simply a question of efficiency and cost but one of access to care and patient survivorship.

Reducing the Human Burden of Breast Cancer: Advanced Radiation Therapy Yields Improved Treatment Outcomes

Radiation therapy is an important modality in the treatment of patients with breast cancer. While its efficacy in the treatment of breast cancer was known shortly after the discovery of x-rays, significant advances in radiation delivery over the past 20 years have resulted in improved patient outcomes. With the development of improved systemic therapy, optimizing local control has become increasingly important and has been shown to improve survival. Better understanding of the magnitude of treatment benefit, as well as patient and biological factors that confer an increased recurrence risk, have allowed radiation oncologists to better tailor treatment decisions to individual patients. Furthermore, significant technological advances have occurred that have reduced the acute and long-term toxicity of radiation treatment. These advances continue to reduce the human burden of breast cancer. It is important for radiation oncologists and nonradiation oncologists to understand these advances, so that patients are appropriately educated about the risks and benefits of this important treatment modality.

Accelerated partial irradiation for breast cancer: systematic review and meta-analysis of 8653 women in eight randomized trials

BACKGROUND AND PURPOSE

Accelerated partial breast irradiation (APBI) is the strategy that allows adjuvant treatment delivery in a shorter period of time in smaller volumes. This study was undertaken to assess the effectiveness and outcomes of APBI in breast cancer compared with whole-breast irradiation (WBI).

MATERIAL AND METHODS

Systematic review and meta-analysis of randomized controlled trials of WBI versus APBI. Two authors independently selected and assessed the studies regarding eligibility criteria.

RESULTS

Eight studies were selected. A total of 8653 patients were randomly assigned for WBI versus APBI. Six studies reported local recurrence outcomes. Two studies were matched in 5 years and only one study for different time of follow-up. Meta-analysis of two trials assessing 1407 participants showed significant difference in the WBI versus APBI group regarding the 5-year local recurrence rate (HR=4.54, 95% CI: 1.78-11.61, p=0.002). Significant difference in favor of WBI for different follow-up times was also found. No differences in nodal recurrence, systemic recurrence, overall survival and mortality rates were observed.

CONCLUSIONS

APBI is associated with higher local recurrence compared to WBI without compromising other clinical outcomes.

Cardiac dose sparing and avoidance techniques in breast cancer radiotherapy

Breast cancer radiotherapy represents an essential component in the overall management of both early stage and locally advanced breast cancer. As the number of breast cancer survivors has increased, chronic sequelae of breast cancer radiotherapy become more important. While recently published data suggest a potential for an increase in cardiac events with radiotherapy, these studies do not consider the impact of newer radiotherapy techniques commonly utilized. Therefore, the purpose of this review is to evaluate cardiac dose sparing techniques in breast cancer radiotherapy. Current options for cardiac protection/avoidance include (1) maneuvers that displace the heart from the field such as coordinating the breathing cycle or through prone patient positioning, (2) technological advances such as intensity modulated radiation therapy (IMRT) or proton beam therapy (PBT), and (3) techniques that treat a smaller volume around the lumpectomy cavity such as accelerated partial breast irradiation (APBI), or intraoperative radiotherapy (IORT). While these techniques have shown promise dosimetrically, limited data on late cardiac events exist due to the difficulties of long-term follow up. Future studies are required to validate the efficacy of cardiac dose sparing techniques and may use surrogates for cardiac events such as biomarkers or perfusion imaging.