Concurrent Radiation and Deep Hyperthermia Therapy for the Treatment of Recurrent Prostate Cancer

PURPOSE/OBJECTIVE(S)

Robustpreclinical and clinical data have established hyperthermia as an effective radiosensitizer which can be used in the setting of recurrent disease to enhance the therapeutic window. We present a single institution experience examining outcomes in recurrent prostate cancer (RPCA) patients treated with concurrent deep hyperthermia (DHT) and radiation (RT). We hypothesized that concurrent DHT and RT would be well tolerated and would provide durable local control without unexpected toxicity.

MATERIALS/METHODS

Consecutive RPCA patients treated with concurrent DHT and pelvic RT were retrospectively analyzed. Patients received twice weekly DHT treatments in addition to daily or twice daily (BID) RT. DHT was delivered using a concentric ring radiofrequency phased array system to a target temperature of 40-43°C. Acute and late treatment associated toxicities, graded per Common Terminology Criteria for Adverse Events (CTCAE) v5.0, were evaluated. Survival and control outcomes were evaluated using the Kaplan-Meier method.

RESULTS

Eighteen patients were included for analysis. Median patient age was 69 yrs (64-82 yrs). Fifteen (83%) patients had received prior RT and 12 (67%) patients had undergone radical prostatectomy. At time of treatment, two patients had RPCA which had dedifferentiated to a small cell phenotype. Eight (44%) patients had extra-pelvic disease at time of treatment. Seventeen (94%) patients received proton RT, while 1 (6%) received photon RT. Median RT dose was 49 Gy (range 30-73.8 Gy). Five (28%) patients received BID RT. Fifteen (83%) patients also received sequential or concurrent systemic therapy including androgen deprivation therapy or chemotherapy. A total of 142 DHT treatments were administered (median of 7.5 treatments). Fourteen (78%) patients completed ≥ 75% of planned DHT treatments. Reasons for inability to complete treatment included discomfort and abnormal vital signs during DHT. Only one patient reported Grade 2 pain and pruritus attributed to concurrent RT and DHT. One acute Grade 3 RT toxicity (diarrhea) was reported. No late Grade 3+ toxicities occurred. Of ten patients (56%) treated with curative intent, 8 (44%) had no reported failures at 2-year follow up while two had distant failure and biochemical failure respectively. Three (17%) patients were treated with palliative intent for disease related pain; two reported partial relief and one reported complete pain relief. With a median follow-up of 27 months (1-46 months), 2-year failure free survival was 41.4% (95% CI: 27.8-55%), local control was 76.5% (95% CI 66.2-86.8%) and overall survival was 70.9% (95% CI 58.4-83.3%).

CONCLUSION

Our results suggest that concurrent RT and DHT is well tolerated and allows for safe escalation of local therapy for RPCA, providing patients with durable local control and palliation with an acceptable toxicity profile. Prospective validation is warranted.

A Precision Medicine Navigator Can Mitigate Inequities Associated with Utilization of Genomic Tests in Black Men with Prostate Cancer

PURPOSE/OBJECTIVE(S)

Black men with prostate cancer in the United States experience disproportionately worse clinical outcomes compared to other racial groups. Identifying more reliable prognosticators to address these inequities has thus been the subject of considerable research scrutiny. However, prognostic genomic tools and genomic biorepositories suffer from an even greater lack of racial diversity. Strategies to mitigate these amplifying developments in inequities are desperately needed. We hypothesized that the presence of a precision medicine navigator (PMN) may mitigate inequities with standard of care (SOC) genomic test utilization among Black men with prostate cancer.

MATERIALS/METHODS

We retrospectively reviewed prostate cancer consults within one healthcare system from 11/2/2021 to 1/2/2022. We compared the frequency of patients who received SOC Decipher or Tempus genomic testing in the 7 months prior to the PMN start (pre-PMN) to the 7 months afterward (post-PMN). Chi square analysis was used to compare subgroups. Binary logistic regression was used to calculate the odds of receiving genomic testing.

RESULTS

The sample included 693 patients, 44.9% (311/693) pre-PMN and 55.1% (382/693) post-PMN, with a median age of 68 in both groups. Pre- and post-PMN racial distributions were similar with 60.1% and 60.2% White, 35.1% and 34% Black, 3.2% and 3.7% Asian/Pacific Islander, and 1.3% and 2.1% Latino, respectively. Pre- and post-PMN NCCN risk category distribution was 15.2% and 10.4% low risk, 46.8% and 49.9% intermediate risk, and 38.1% and 39.7% high risk, respectively. Pre- and post-PMN groups had 14.5% and 17% distant metastases, 77.2% and 76.9% localized disease, 10.3% and 10% prior prostatectomy, 47% and 51% income below sample median, 51% and 52% with Medicare/Medicaid, and 47% and 48% seen at community hospitals, respectively. There were no statistically significant differences for these variables pre- and post-PMN. However, from pre- to post-PMN, the proportion of Black patients receiving genomic testing increased from 19% to 58%. Black patients seen post-PMN were six times more likely to receive testing (p<0.001). Significant increases in SOC genomic testing post-PMN also occurred among lower median income patients, patients with Medicare/Medicaid, and community hospital patients.

CONCLUSION

The presence of a PMN may improve disparate rates of Black patients receiving SOC genomic tests for prostate cancer compared to other racial groups and may alleviate genomic testing inequities among other demographics.

Relationship Between Spatial Distribution Tumor Location and Dosimetric Outcomes in Patients Receiving Definitive Proton Therapy for Locally Advanced Lung Cancer

PURPOSE/OBJECTIVE(S)

Intensity Modulated Proton Therapy with Pencil Beam Scanning (IMPT/PBS) has been postulated to have dosimetric benefits, especially for sparing of normal tissues in the treatment of thoracic malignancies. Distinguishing which patients may benefit most from IMPT/PBS treatment has important implications when counseling patients on optimal treatment modality, treatment approval turnaround time, and potential toxicities. We herein present a single institution experience assessing the relationship between spatial distribution of tumor location and dosimetric outcomes in patients receiving definitive IMPT/PBS for locally advanced lung cancer.

MATERIALS/METHODS

Consecutive patients treated with IMPT/PBS for locally advanced lung cancer from 2016-2022 at an academic proton center were retrospectively analyzed. Treatment, tumor volume, and patient characteristics were collected. Distance from the posterior pleura to the anterior-most portion of the clinical tumor volume (CTV) of the tumor was measured. A ratio of this distance to the pleura-to-pleura distance at that corresponding lung level was used to classify anterior (>0.7) versus posterior tumors. Dosimetric details including beam angles, dose-volume parameters for the ipsilateral, contralateral, total lung and heart for each patient were recorded. Statistical differences between groups were determined using Wilcoxon Signed Rank test. Pearson's correlation coefficient was used to determine impact of CTV volume and the anterior-most distance of CTV on dosimetric parameters.

RESULTS

Fifty-eight patients treated for Stage IIB-IIIC locally advanced lung cancer with a median CTV volume of 258 cc's were identified and included in this retrospective study. Median age was 68 years and there was an equal distribution of male (29, 50%) and female patients (29, 50%) as well as anterior (>0.7) and posterior lying tumors in this cohort. The majority of patients were white (42, 72%) Forty patients (69%) had right sided lung tumors. Median cumulative dose was 61.2 Gy (range 59.4-70 Gy) while median dose per fraction was 2 Gy (range 1.8-2 Gy). When compared to anterior tumors, posterior tumors had a lower Lung V20 (19.1% vs 21.6%, p = 0.1,), V5 (27.6% vs 32.4%, p = 0.03), Mean Lung (9.9 Gy vs 11.7 Gy, p = 0.04), Mean Heart (4.8 Gy vs 6.3 Gy, p = 0.1), and Heart V50 (3.1% vs. 4.6%, p = 0.15). Anterior-most distance of CTV from the posterior pleura was positively correlated with Lung V20 (r = .435, p = 0.001), Lung V5 (r = .390, p = 0.002), Mean Lung (r = .479, p = 0.001), Mean Heart (r = .304, p = 0.020), and Heart V50 (r = .322, p = 0.014). CTV volume was also significantly positively correlated (p <.01) with these parameters.

CONCLUSION

Spatial distribution and treatment volume size are predictive of dosimetric outcomes for locally advanced lung cancer. Posterior lying tumors may derive greater dosimetric advantage when compared to anterior lesions when utilizing IMPT/PBS.