Smart Solutions to Address the Global Gap in Radiation Oncology Through Trainee Engagement and Partnerships with Industry

Radiation therapy is a critical modality for cancer treatment. Greater than 80% of the global population lack access to and expertise with the technological advancements that allow for state-of-the-art treatments that are more accessible in the West. What follows is a review of a two-pronged solution to help address this global gap to technology and innovation: (1) trainee engagement and (2) industry partnerships. We hope to galvanize our readers to see the immense potential for success if we may synergize efforts in education and with our partners in private industry to help address critical unmet needs in emerging economies of the globe.

Implementing a simulation-based curriculum for hybrid intracavitary/interstitial brachytherapy using a new, commercially available, US/MR/CT-compatible gynecologic phantom

PURPOSE

To establish a simulation-based workshop for teaching hybrid intracavitary/interstitial (IC/IS) brachytherapy skills using a new, commercially available US/CT/MRI-compatible gynecologic phantom prototype.

METHODS AND MATERIALS

The VIOMERSE gynecological trainer phantom consisted of tissue-like colloid material and was US, CT, and MRI-compatible. We designed a hands-on workshop incorporating the phantom prototype to teach skills for hybrid IC/IS brachytherapy including pre-implant planning, procedural steps of implant placement, and post-implant evaluation. The workshop impact was evaluated with pre- and post-workshop surveys and responses were analyzed with Wilcoxon matched-pairs signed-rank test.

RESULTS

Thirteen residents, divided into small groups, attended one of three separate 1-h workshop sessions held during the gynecologic education block. Workshop steps included IC applicator placement, tumor mapping and pre-planning desired location and depth of needles for hybrid IC/IS application, IS needle labelling and insertion, image review of needle placements, comparison of IC-alone versus IC/IS brachytherapy plans. Responses to questions ascertaining knowledge, confidence, and ability in planning and executing hybrid IC/IS procedures all demonstrated significant improvement from pre- to post-workshop. In response to whether the session was an effective learning experience, all residents rated the workshop with a score of 9 (n = 1) or 10 (n = 12) out of 10, with a score of 10 indicating "strongly agree."

CONCLUSIONS

Implementation of a hybrid IC/IS brachytherapy workshop utilizing a new, commercially-available phantom prototype was successful, with clear, subjective benefit for the residents in our program. This experience may inform continued efforts towards standardizing brachytherapy curricula across programs and increasing trainee exposure to interstitial procedures.

Declining use of inguinofemoral lymphadenectomy in the treatment of clinically negative, pathologic node positive vulvar cancer

PURPOSE

The management of vulvar cancer with clinically negative groin lymph nodes but with positive sentinel lymph node biopsy (SLNB) is controversial, with options including inguinofemoral lymphadenectomy (IFL) and/or adjuvant chemotherapy and radiotherapy. We used the National Cancer Database (NCDB) to examine trends in the management of clinically node negative, pathologically node positive (cN-/pN+) patients.

METHODS

The NCDB was used to identify cN-/pN+ vulvar cancer patients. Demographic and clinical data were compared with chi-squared and Wilcoxon rank-sum tests. OS was analyzed with the Kaplan-Meier method and log-rank test. Cox proportional hazards regression was used to determine factors associated with OS.

RESULTS

A total of 885 cN-/pN+ vulvar cancer patients were identified between 2012 and 2016, during which the rate of SLNB alone increased from 3.6% to 11.7%, while the rate of IFL +/- SLNB decreased from 89.7% to 78.1% (p < 0.05). Radiation was used in 68.5% and 64.6% of the SLNB-alone and IFL +/- SLNB cohorts, respectively, with chemoradiation in 37.1% and 33.6%, respectively. OS was not different between patients who received SLNB-alone vs. IFL +/- SLNB (p = 0.644). Receipt of chemotherapy and radiation was associated with improved OS (p < 0.001).

CONCLUSIONS

Among cN-/pN+ vulvar cancer patients in the NCDB, the practice of performing IFL decreased over time as SLNB-alone became more common and the majority received radiation +/- chemotherapy. There was no difference in OS between SLNB-alone vs. IFL +/- SLNB. Patients treated with adjuvant chemoradiation had improved survival. Whether the favorable outcomes in the SLNB-alone cohort may be attributed to radiotherapy dose escalation or use of chemotherapy warrants further study.

Standard Tangential Radiation Fields Do Not Provide Incidental Coverage to the Internal Mammary Nodes

PURPOSE

The purpose of the study was to evaluate the incidental dose delivered to the internal mammary nodes (IMNs) in patients treated with tangential 3-dimensional conformal radiation therapy and to identify potential parameters that may affect the IMN mean dose.

METHODS AND MATERIALS

The study cohort consisted of 362 consecutively treated patients with breast cancer in our center between January 2015 and July 2017 who had received adjuvant whole-breast radiation therapy or postmastectomy radiation with or without a supraclavicular ± axillary field and without intentional inclusion of the IMN chain. The clinical target volume (CTV) for the IMNs was contoured per the Radiation Therapy Oncology Group 3509/3510 protocol and was then divided into 3 subregions: upper, mid, and lower thirds. The planning target volume for the IMNs was generated by adding 5 mm to the CTV. The primary endpoint was to assess the V40 (volume receiving 40 Gy) to the IMN planning target volume and its potential influencing parameters using a linear regression model.

RESULTS

The mean (±standard deviation) dose to the CTV IMN chain was 36% ± 28.7%. The Kruskal-Wallis test demonstrated significant differences in the median dose delivered to each level: upper third (7.2%), mid third (21.5%), and lower third (41.7%) (P < .001). The mean V40 IMN planning target volume was 14.2% (standard deviation, 18.7%). Presternal fat thickness (regression coefficient [RC] = -16.4; P < .001), postmastectomy radiation (RC = 24; P < .001), reconstruction after mastectomy (RC = -22.4; P < .001), and the addition of a supraclavicular field (RC = 8.8; P = .03) were all significantly associated with IMN mean dose.

CONCLUSIONS

For patients receiving standard breast/chest wall tangential radiation fields, the IMN chain is not incidentally covered with therapeutic doses in the vast majority of cases. Therefore, if regional nodal radiation is intended to include the IMNs, contouring and careful plan review are necessary to ensure adequate therapeutic coverage.

Rectum and bladder spacing in cervical cancer brachytherapy using a novel injectable hydrogel compound

PURPOSE

The aim of this study was to evaluate injection of a novel hydrogel (TraceIT; Augmenix, Waltham, MA) between the cervix, rectum, and bladder in female cadavers compared with, and in addition to, the current standard of gauze packing, for organ-at-risk sparing in cervical cancer brachytherapy planning.

METHODS AND MATERIALS

This brachytherapy cadaver study used T2-weighted MRI and CT imaging to compare three scenarios: (1) gauze packing alone, (2) hydrogel injection placed in the cervical fornices and rectovaginal septum, and (3) gauze packing in conjunction with hydrogel injection. Hydrogel distribution was evaluated. Doses to 2 cm³ volumes (D_2cc) for the rectum, bladder, and sigmoid were collected. Statistical significance (p < 0.05) was evaluated using a two-tailed paired t test.

RESULTS

Hydrogel was successfully injected to space the bladder and rectum from the cervix in all five cadavers. The spacer was easily identifiable on both CT and MRI. The use of hydrogel in addition to packing resulted in a 22% decrease in rectum D_2cc dose (p = 0.02), a 10% decrease in bladder D_2cc (p = 0.27), and no change in sigmoid D_2cc dose. No difference was observed between hydrogel only vs. gauze packing only.

CONCLUSIONS

Our results revealed a significant clinically meaningful decrease in rectal D_2cc associated with the use of hydrogel in addition to gauze packing-TraceIT hydrogel holds promise as a spacer in cervical cancer therapy.