ADT Use and Nodal Irradiation in Men Receiving Post-Prostatectomy Salvage Radiotherapy within a Statewide Radiation Oncology Quality Consortium

PURPOSE/OBJECTIVE(S)

For men with biochemical recurrence after radical prostatectomy, salvage radiotherapy (SRT) is a standard of care. Outcomes are improved when SRT is delivered at lower PSA levels, and there has been increased emphasis on more timely treatment. With early SRT, however, there remains uncertainty as to the optimal use and duration of androgen deprivation therapy (ADT) and pelvic lymph node radiation (PLNRT). Moreover, PET imaging and genomic classifiers have emerged as tools to guide treatment decisions, but their uptake in routine practice is unknown. To address these questions, we analyzed a contemporary cohort treated with SRT within the Michigan Radiation Oncology Quality Consortium (MROQC). We hypothesized that ADT and PLNRT practices would reflect recent trial results in this setting.

MATERIALS/METHODS

Eligible patients receiving SRT at an MROQC center were enrolled from 06/09/20 to 11/04/22. Data was prospectively collected via patient-, physician-, and physicist-completed forms. Patients were matched to the Michigan Urological Surgery Improvement Collaborative (MUSIC) database for additional treatment- and patient-related data. Univariable (UVA) and multivariable analyses (MVA) were performed to test associations between patient/tumor factors and ADT or PLNRT use.

RESULTS

A total of 191 patients across 26 centers were enrolled in the MROQC database. Of these, 116 were matched to the MUSIC database. Median time from RP to SRT was 17 months (IQR 8 - 33 months). The median post-RP PSA prior to SRT was 0.25 (IQR 0.16 - 0.60). Early SRT was defined as pre-SRT PSA ≤0.5, and 27% (n = 31/116) had a pre-SRT PSA >0.5. Twenty-eight were pT3b/T4, 97% were pN0/NX, and 51% had positive surgical margins. Fractionation was conventional (>28 fractions) in 58% and moderate hypofractionation (20-28 fractions) in 38%. Table 1 describes the patients receiving ADT and/or PLNRT. Median ADT duration was 6 mo (IQR 6 - 7 mo). MVA revealed pre-SRT PSA >0.5 (OR 5.05 [1.89 - 15.33]) and pT3b/T4 disease (OR 4.23 [1.40 - 14.56]) were significantly associated with ADT use (p <0.05), but not grade group (GG) or margin status. PLNRT was significantly associated with pre-SRT PSA >0.5 (OR 3.04 [1.21 - 8.42], p <0.05) but not pT stage, margin status, or GG. PET imaging was performed in 37% of men (52% negative, 21% prostate bed alone uptake, and 26% lymph node positivity) and genomic classifiers were performed in 24%.

CONCLUSION

Nearly 75% of biochemically recurrent prostate cancer patients within MROQC received early SRT, and about half received ADT. A pre-SRT PSA >0.5 was strongly associated with ADT and PLNRT. With prostate bed SRT alone, very few received ADT. Given the considerable heterogeneity in treatment, additional studies may help identify patients who most benefit from ADT + PLNRT, and who may be spared potential added toxicity.

Hyaluronic Acid Rectal Spacer Stability during Radiation Therapy for Localized Prostate Cancer: An Intercontinental Study

PURPOSE/OBJECTIVE(S)

Despite IGRT and IMRT current techniques, rectal toxicity remains a significant problem after prostate cancer radiation therapy but implanted rectal spacers have successfully reduced toxicity rates. We are reporting the results of an intercontinental prospective rectal spacer trial performed at 13 centers in Spain, Australia, and USA. Our hypothesis was that the separation created between the prostate and anterior rectal wall was stable between the time of implant and a 3-month follow-up.

MATERIALS/METHODS

Our prospective multicenter study was approved by the corresponding IRBs and patients signed informed consent. It was performed between February - June 2021. Patients were imaged using T2 MRI immediately post-implant (MRI-1) and at 3 months (MRI-2). We analyzed the dimensions of hyaluronic acid (HA) rectal spacer inserted for low - intermediate risk prostate cancer treated with EBRT. The rectal displacement was determined by measuring the separation at 3 different levels: prostate midline, midgland +1cm (superior), and midgland -1 cm (inferior), from the posterior prostate capsule to the anterior rectal wall. The core laboratory performed the measurement for all sites. The confidence interval (CI) was computed using a Student's t-distribution.

RESULTS

A total of 136 patients randomized to the Barrigel arm underwent HA rectal spacing with 100% placement success rate. There were no device failures or surgical complications. Of these, 6 were lost to follow-up. The averages of the remaining 130 patients at the 3 perirectal distances were 13.04 mm +/- 3.1 mm and 12.79 mm +/- 3.5 mm for MRI-1 and MRI-2, respectively with an average difference of -0.17 mm +/- 3.48 mm. Additional parameters are listed on the table.

CONCLUSION

The results demonstrate the stability of the HA-created separation at the three different prostatic levels for up to 3 months. These findings show dimensional stability well within standard clinical margins. This indicates reliability for HA use in most clinics, as the results are relevant in the setting of dose escalation or ultra-hypofractionation schedules, as well as conventional fractionation.

Cannabis Use Patterns among Patients with Early-Stage Breast Cancer in a Large Multicenter Cohort from a State with Legalized Adult Non-Medical Cannabis

PURPOSE/OBJECTIVE(S)

Cannabis use among patients with cancer is an area of great interest given its widespread acceptance despite the lack of supporting clinical data. The absence of data limits the understanding of potential clinical benefits of cannabis and the ability of providers to deliver evidence-based recommendations for patient care. We explored cannabis use patterns in patients with early-stage breast cancer in a large multicenter cohort in a state with legalized adult non-medical cannabis.

MATERIALS/METHODS

Initial questions about cannabis use history and frequency were introduced in Michigan Radiation Oncology Quality Consortium (MROQC) breast cancer patient surveys on 2/1/2020 for female patients receiving radiation after lumpectomy for non-metastatic breast cancer. Expanded questions were introduced on 6/28/2022 to assess mode of administration, active ingredient, and reason for use. Summary statistics were generated. A multivariable model using logistic regression identified patient characteristics associated with cannabis use.

RESULTS

Among 3948 eligible patients, 2738 (69.35%) completed survey questions, and 2462/2738 (89.9%) completed the initial question on cannabis use. Among those, 364/2462 (14.8%) noted cannabis use in the last 30 days, 588 (23.9%) noted remote use (>30 days ago), 1462 (59.4%) reported never having used cannabis, 44 (1.8%) preferred not to answer cannabis use questions, and 4 (0.4%) did not provide use history. Younger age [age <50 vs 60-70, OR 2.5 (95% CI 1.65, 3.79) p<0.001)], Hispanic ethnicity [OR 2.20 (95% CI 1.06, 4.56) p = 0.03], history of smoking [OR 2.56 (95% CI 1.88, 3.48) p<0.001], current smoking [OR 4.70 (95% CI 3.22, 6.86) p<0.001)], and prior chemotherapy [OR 1.40 (95% CI 1.00, 1.96) p = 0.05] predicted recent cannabis use in a multivariable model. Of the 364 patients endorsing cannabis use in the last 30 days, 89 (24.5%), 72 (19.8%), 29 (8.0%), 66 (18.1%), 30 (8.2%), and 78 (21.4%) reported using cannabis 1-2 days, 3-5 days, 6-9 days, 10-19 days, 20-29 days, and all 30 days, respectively. The most common modes of administration among 76 individuals who responded to the expanded questionnaire to date were oral (39.4%), smoking (30.3%), and topical (10.5%). The products used contained tetrahydrocannabinol (THC; 26.3%), cannabidiol (CBD; 19.7%), balanced levels of THC and CBD (19.7%), or active ingredients that were unknown to the patient (34.2%). Patients frequently endorsed cannabis use for insomnia, anxiety, and pain.

CONCLUSION

Many patients with early-stage breast cancer are using cannabis. Younger age, Hispanic ethnicity, smoking, and chemotherapy history are predictors of cannabis use. Patients are often unaware of the active ingredients in the products that they use, suggesting an important role for patient education and a need to equip providers to advise patients in their care.

Androgen Deprivation Therapy Use among Intermediate Risk Prostate Cancer Patients Undergoing Radiation Therapy across a Statewide Radiation Oncology Quality Consortium

PURPOSE/OBJECTIVE(S)

For men with intermediate (INT) risk prostate cancer, the addition of androgen deprivation therapy (ADT) reduces risk of PSA failure, distant metastasis, and cancer-related mortality. Moreover, the relative reduction in cancer-related adverse outcomes with ADT use appears consistent across all INT risk subgroups. The absolute benefit of ADT, however, varies by baseline risk. In contemporary practice, it is unknown which clinical factors are most strongly associated with intended ADT use. Therefore, we sought to identify such factors within the diverse practices of the Michigan Radiation Oncology Quality Consortium (MROQC).

MATERIALS/METHODS

Patients with localized prostate cancer undergoing definitive radiation therapy were enrolled from 6/9/20 to 11/4/22 (n = 599). Standardized patient, physician, and physicist forms were used to collect baseline and follow-up information. Intended ADT use, defined by the treating physician, was prospectively collected and is the primary outcome of this analysis. Univariable (UVA) and multivariable analyses (MVA) associations with patient (age, race, comorbidities), tumor (T stage, Gleason, percent cores positive, and PSA), and practice-related (academic vs private) factors were performed. In addition, advanced modality testing (PET, MRI, and genomic classifiers) was available as of March 2021, and subgroup analysis were performed where appropriate.

RESULTS

A total 351 patients across 26 centers were enrolled with INT risk disease. ADT use was intended for 46% of men (n = 162/351) which differed by men with NCCN favorable INT (21%, n = 22/105) vs unfavorable INT risk disease (57%, n = 140/246), p<0.001. Sixty two percent (n = 100/162) had an intended ADT duration of 4-6 months and 21% (n = 34/162) had ≥12 months. Older age was associated with ADT use (70 vs 67, p < 0.01); there were no significant differences by race or comorbidities number. MVA showed Gleason 4+3 (OR 4.61 [2.91 - 7.42]) and > = 50% positive cores (2.56 [1.52 - 4.37]) were significantly associated with ADT use. No significant differences were noted based on practice setting. Pelvic MRI was obtained for 71% of men (n = 197/279), genomic classifiers in 47% (n = 130/279), and PET in 2% (n = 6/282). In the subset with MRI (n = 197), adverse features (ECE, SVI, or equivocal LNs) were associated with intended ADT use (OR 3.0 [1.4 - 7.1]) after adjustment for NCCN favorable/unfavorable INT risk classification.

CONCLUSION

Within a state-wide consortium, intended ADT use for intermediate prostate cancer is most strongly associated with Gleason score, ≥50% positive cores, NCCN unfavorable intermediate risk classification, and adverse features on MRI. Nearly half of men had genomic classifier testing underscoring the importance ongoing trials such as NRG/GU 010.

Dosimetric Predictors for Acute Esophagitis during Radiation Therapy for Lung Cancer: An Update of a Large Statewide Observational Study

PURPOSE/OBJECTIVE(S)

Acute esophagitis remains a clinical challenge during the treatment of locally advanced non-small cell lung cancer (NSCLC). Here, we analyze the dosimetric and patient-level characteristics associated with acute grade 2+ and 3+ esophagitis in patients undergoing radiation therapy for NSCLC across a statewide consortium.

MATERIALS/METHODS

Demographic, dosimetric, and acute toxicity data were prospectively collected for patients undergoing definitive radiation therapy +/- chemotherapy for stage II-III NSCLC from 2012-2022 across the Michigan Radiation Oncology Quality Consortium (MROQC). Logistic regression models were used to characterize the risk of grade 2+ and 3+ esophagitis as a function of dosimetric and clinical covariates. Multivariate regression models were fitted to predict the 50% risk of grade 2 esophagitis or 3% risk of grade 3 esophagitis at each dose value.

RESULTS

Of 1760 patients evaluated, 84.2% had stage III disease and 85.3% received concurrent chemotherapy. 79.2% of patients had an ECOG performance status ≤1. Rates of acute grade 2+ and 3+ esophagitis were 48.4% and 2.2%, respectively. On multivariate analyses, performance status, mean esophageal dose and esophageal D2cc were significantly associated with grade 2+ and 3+ esophagitis. Concurrent chemotherapy was associated with grade 2+ but not grade 3+ esophagitis. Dose-response relationships were modeled for grade 2+ and 3+ esophagitis by mean esophageal dose and esophageal D2cc, stratified by performance status and/or receipt of concurrent chemotherapy. For all patients, mean esophageal dose of 29 Gy and esophageal D2cc of 61 Gy corresponded to a 3% risk of acute grade 3+ esophagitis. For patients receiving chemotherapy, mean esophageal dose of 22 Gy and esophageal D2cc of 49.5 Gy corresponded to a 50% risk of acute grade 2+ esophagitis.

CONCLUSION

Performance status, concurrent chemotherapy, mean esophageal dose and esophageal D2cc are associated with acute esophagitis during definitive treatment of NSCLC. Models that quantitatively account for these factors can be useful in individualizing radiation plans. Mean esophageal dose of 29 Gy and esophageal D2cc of 61 Gy corresponded to a 3% risk of acute grade 3+ esophagitis and merit consideration as contemporary treatment planning constraints.