Stereotactic body radiotherapy for apical lung tumors: Dosimetric analysis of the brachial plexus and preliminary clinical outcomes

BACKGROUND

Dosimetric constraints of the brachial plexus have not yet been well-established for patients undergoing stereotactic body radiotherapy (SBRT). This study evaluated long-term experience with the treatment of early stage apical lung tumors with SBRT and reports on dosimetric correlates of outcome.

METHODS

Between 2009 and 2018, a total of 78 consecutive patients with 81 apical lung tumors underwent SBRT for T1-3N0 non-small cell lung cancer. Apical tumors were those with tumor epicenter superior to the aortic arch. The brachial plexus (BP) was anatomically contoured according to the Radiation Therapy Oncology Group (RTOG) atlas. Patient medical records were retrospectively reviewed to determine incidence of brachial plexus injury (BPI) and a normal tissue complication probability model (NTCP) was applied to the dosimetric data.

RESULTS

Five patients (6.4%) reported neuropathic symptoms consistent with BPI and occurred a median 11.9 months after treatment (range, 5.2 to 28.1 months). Most common dose and fractionation in those developing BPI were 50 Gy in 5 fractions (4 patients). Symptoms consisted of pain in 2 patients (40.0%), numbness in the hand or axilla in 4 patients (80.0%), and ipsilateral hand weakness in 1 patient (20.0%). In the overall cohort the median BP Dmax (EQD2_{3 Gy}) was 5.13 Gy (range, 0.18 to 217.2 Gy) and in patients with BPI the median BP Dmax (EQD2_{3 Gy}) was 32.14 Gy (range, 13.4 to 99.9 Gy). The NTCP model gave good fit with an area under the curve (AUC) of 0.75 (OR 7.3, 95% CI: 0.8-68.3) for BP Dmax (EQD2_{3 Gy}) threshold of 20 Gy.

CONCLUSION

Significant variation exists in the dose delivered to the brachial plexus for patients treated by SBRT for apical lung tumors. The incidence of neuropathic symptoms in the post-SBRT setting was appreciable and prospective clinical correlation with dosimetric information should be utilized in order to develop evidence-based dose constraints.

Implications of Medical Board Certification Practices on Family Planning and Professional Trajectory for Early Career Female Radiation Oncologists

PURPOSE

Our purpose was to evaluate the effect of the current structure and schedule of the American Board of Radiology (ABR) radiation oncology initial certification (RO-IC) examinations, with a primary focus on implications for family planning and early professional barriers among female radiation oncologists.

METHODS AND MATERIALS

A survey was conducted of crowdsourced ABR candidates and diplomates for radiation oncology between June and July of 2020. The primary study cohort was early career female radiation oncologists of the 2016 through 2021 graduating classes.

RESULTS

The survey response rate of early career female radiation oncologists was 37% (126 of an estimated 337). Among this cohort, 58% (73 of 126) reported they delayed or are currently delaying/timing pregnancy or adoption to accommodate the annual schedule of the 4 qualifying and certifying examinations required to achieve board certification in radiation oncology. One in every 3 respondents who had attempted to become pregnant reported experiencing infertility (25 of 79, 32%). Women who reported intentionally delaying pregnancy to accommodate the ABR RO-IC examination schedule were significantly more likely to experience infertility (46% vs 18%, P = .008). Seven women (6%) reported at least a 1-year delay in sitting for a RO-IC examination due to an unavoidable scheduling conflict related to childbirth and/or the peripartum period. A majority reported that full board certification had a significant effect on achieving academic promotion or professional partnership (52%), annual compensation (54%), and nonclinical professional commitments (58%) - these rates mirror those of surveyed early career male counterparts (n = 101).

CONCLUSIONS

The current structure and scheduling of the ABR RO-IC examinations imposes noteworthy hurdles for many female radiation oncologists when entering the workforce. The recent transition to virtual examination platforms creates an important opportunity to increase flexibility in the structure and scheduling of the board examination process to improve equitable board certification practices.

#WomenWhoCurie: Leveraging Social Media to Promote Women in Radiation Oncology

The proportion of female trainees in radiation oncology has generally declined despite increasing numbers of female medical students; as a result, radiation oncology is among the bottom 5 specialties in terms of the percentage of female applicants. Recently, social media has been harnessed as a tool to bring recognition to underrepresented groups within medicine and other fields. Inspired by the wide-reaching social media campaign of #ILookLikeASurgeon to promote female physicians, members of the Society for Women in Radiation Oncology penned a new hashtag and launched the #WomenWhoCurie social media campaign on Marie Curie's birthday November 7th, as part of their strategy to raise public awareness. From November 6, 2018 until November 10, 2018, the #WomenWhoCurie hashtag delivered 1,135,000 impressions, including 408 photos from all over the world including United States, Spain, Canada, France, Australia, Ireland, the United Kingdom, Mexico, Japan, the Netherlands, India, Ecuador, Panama, Brazil, and Nigeria. Alongside continued gender disparity research, social media should continue to be used as a tool to engage the community and spur conversations to formulate solutions for gender inequity.

Current Therapeutic Approaches to DCIS

Treatment for ductal carcinoma in-situ (DCIS) has historically been extrapolated from studies of invasive breast cancer. Accepted local therapy approaches range from small local excisions, with or without radiation, to bilateral mastectomies. Systemic treatment with endocrine therapy is often recommended for hormone positive patients. With improvements in imaging, pathologic review, and treatment techniques in the modern era, combined with new information regarding tumor biology, the management of DCIS is rapidly evolving. A multidisciplinary approach to treatment is now more important than ever, with a shift towards de-escalating therapy to reduce treatment related toxicity. This review focuses on nuances of clinical management of DCIS in the modern era, highlighting key differences between DCIS as compared to invasive breast cancer. The American Cancer Society (ACS) currently recommends beginning screening with annual mammograms for women age 45, with the option to start at age 40. As treatment of DCIS has not been shown to impact survival, the USPSTF has more conservative screening recommendations of biennial mammograms from age 50-74. Unlike invasive breast cancer, DCIS is almost exclusively diagnosed by mammographic detection, and lymph node evaluation is not recommended. Pathologic review of biopsy specimens should follow the guidelines of the College of American Pathologists. Surgical management options include breast conservation, mastectomy, or possibly nipple sparing mastectomy, with upfront sentinel lymph node evaluation in the case of mastectomy. Radiation therapy is generally recommended as a component of breast conserving therapy for patients with DCIS, though in some low risk patients, there is trial data to suggest that adjuvant radiation may be omitted. Techniques for minimizing radiation toxicity should always be emphasized. Endocrine therapy is offered to women with hormone positive DCIS who have undergone lumpectomy for risk reduction, and has the benefit of decreasing incidence of events in both the ipsilateral and contralateral breast. More recent studies have explored use of targeted treatments such as trastuzumab in DCIS for HER2 overexpression. Future directions include tailoring therapy based on patient characteristics and tumor biology. With so many different options for treatment, it is also critical to engage in a discussion with the patient to arrive at a treatment decision that balances patient preferences for disease control versus treatment toxicity, financial toxicity, cosmesis, and quality of life.

Dosimetric effects of deep inspiration breath hold for radiation treatment of esophageal cancer based on tumor location

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Background: Deep inspiration breath hold (DIBH) has been shown to reduce heart and lung doses in radiation treatment of breast cancer and lymphoma. We investigated its application for treatment of esophageal cancer. Methods: Five patients who had DIBH simulation for diagnoses with chest scans were studied. Patients were simulated supine with 2 CT scans each: free breathing (FB) and DIBH using surface infrared markers. The patients were contoured using standard volumes as per RTOG 1010, including a 45 Gy planning target volume (PTV). Both a mid-esophagus and distal PTV were created for each of the model patients, by contouring 5 cm tumor volumes at the level of the carina and gastroesophageal junction. Normal structures were contoured as well. For distal tumors, the celiac nodes were covered electively as per RTOG 1010. Uniform three dimensional conformal radiotherapy plans were generated and normalized to provide 100% dose coverage to 95% of the PTV. Dose volume histograms were generated and evaluated. A 2-tailed paired student’s T-test was used to evaluate statistical significance. Results: When comparing the changes in dose to the normal structures with breath hold, a contrasting trend was seen between proximal and distal tumors. The mean heart dose and V40 decreased with breath hold for proximal tumor plans, however the heart dose metrics increased with breath hold for distal tumors. For the proximal tumor plans, the lung mean, V20, V10 and V5 decreased with breath hold in all patients. For distal tumors, mean lung doses trended towards an increase. Conclusions: Dosimetric parameters uniformly improved for proximal tumors with DIBH. By contrast, distal tumors often showed worsening of heart and lung dosimetry with DIBH. This appeared to be related to entry of the lung volume into the celiac nodal field, among other factors. [Table: see text]