Evaluation of Radiation-induced Pleural Effusions after Radiotherapy to Support Development of Animal Models of Radiation Pneumonitis.

ABSTRACT: Not all animal models develop radiation-induced pleural effusions (RIPEs) as a form of radiation-induced lung injury (RILI). Such effusions are also not well characterized in humans. The purpose of this study is to identify occurrences of RIPE in humans, provide justification for development of relevant animal models, and further characterize its risk factors in cancer patients. We also aim to identify dose thresholds for cardiopulmonary toxicity in humans to shed light on possible pathogenic mechanisms for RIPEs. We carried out a retrospective review of medical records of 96 cancer patients receiving thoracic irradiation (TRT) at our institution. Fifty-three (53%) patients developed a new pleural effusion post TRT; 18 (19%) had RIPE; and 67% developed RIPE ipsilateral to the site irradiated. None developed "contralateral only" effusions. Median time to development was 6 mo (IQR; 4-8 mo). Of 18, 8 patients (44%) had concomitant asymptomatic (radiographic only) or symptomatic radiation pneumonitis and pericardial effusion. Dosimetric factors, including combined and ipsilateral mean lung dose (MLD), were significantly associated with increased risk of RIPE. Angiotensin converting enzyme inhibition, steroids, or concurrent chemotherapy did not modify incidence of RIPE. Our results substantiate the occurrence and incidence of RIPEs in humans. In cancer patients, a median time to development of effusions around 6 mo also supports the onset of RIPEs concurrent with radiation pneumonitis. Future work needs to include large populations of cancer survivors in whom delayed RIPEs can be tracked and correlated with cardiovascular changes in the context of injury to multiple organs.

Dosimetric Predictors of Cardiotoxicity in Thoracic Radiotherapy for Lung Cancer.

BACKGROUND: Higher cardiac radiotherapy (RT) doses when treating lung cancer are associated with worse overall survival (OS), although the direct association between cardiac dose and early cardiotoxicity is poorly understood. We hypothesized that RT doses to the heart and cardiac substructures are associated with under-reported early cardiotoxicity and worse OS. PATIENTS AND METHODS: We conducted an institutional retrospective review of lung cancer patients treated with conventionally fractionated RT from 2010 to 2015. Collected data included pre-RT cardiac risk factors, post-RT cardiotoxicities, and dose-volume parameters for cardiac substructures. Univariate and multivariate analyses were performed to identify predictors of cardiotoxicity and OS. RESULTS: Seventy-six cases were evaluated with 1.2 years median follow-up. Cardiotoxicities included atrial arrhythmia (n = 5), pericardial effusion (n = 16), and valvular disease (n = 1). In univariate analysis, significant dose-volume predictors for cardiotoxicity included mean RT dose to structure of interest, volume of structure of interest receiving ≥30 Gy RT dose, and volume of structure of interest receiving ≥45 Gy RT dose (V45) to the atria, ventricles, and pericardium. Higher ventricular V45 was associated with post-RT cardiotoxicity in multivariate analysis (hazard ratio [HR], 1.50; P = .027). Cardiotoxicity occurrence was a highly significant predictor of OS in multivariate analysis (HR, 12.7; P < .001), but higher ventricular V45 alone was not (HR, 0.78; P = .450). CONCLUSION: Early cardiac events were relatively common after lung cancer RT and associated with multiple cardiac dose-volume parameters. Occurrence of early cardiotoxicity was strongly associated with worse OS. In practice, early cardiotoxicity is under-reported, supporting the need for more detailed cardiac evaluations in high-risk patients to detect and address early cardiotoxicity.

Digital Rectal Examination Remains a Key Prognostic Tool for Prostate Cancer: A National Cancer Database Review.

BACKGROUND: Prostate cancer clinical stage T2 (cT2) subclassifications, as determined by digital rectal examination (DRE), are a historic method of staging prostate cancer. However, given the potential discomfort associated with prostate examination and the wide availability of other prognostic tests, the necessity of DRE is uncertain. This study sought to determine the prognostic value of the prostate cancer cT2 subclassifications in a contemporary cohort of patients. METHODS: The National Cancer Database was used to identify a cohort of men with high-risk clinical T2N0M0 prostate cancer treated with external-beam radiotherapy and androgen deprivation therapies ± surgery from 2004 to 2010. We assessed overall survival from a landmark time of 10 months using Kaplan-Meier and log-rank test analysis. A multivariate proportional hazards model was used to estimate the simultaneous effects of multiple factors, including cT2 subclassification and other well-established prognostic indicators of overall survival in prostate cancer. RESULTS: A total of 5,291 men were included in the final analysis, with a median follow-up of 5.4 years. The cT2a, cT2b, and cT2c subclassifications demonstrated increasing hazard ratios of 1.00 (reference), 1.25 (95% CI, 1.07-1.45; P=.0046), and 1.43 (95% CI, 1.25-1.63; P<.0001), respectively, reflecting a higher probability of death with each incremental increase in cT2 subclassification. This finding was independent of other known prognostic variables on multivariate analysis. CONCLUSIONS: Results show that cT2 subclassifications had independent prognostic value in a large and contemporary cohort of men. cT2 classification remains an important, low-cost prognostic tool for men with prostatic adenocarcinoma. The clinical relevance of this test should be appreciated and accounted for by providers treating prostate adenocarcinoma.

Increased tumor response to neoadjuvant therapy among rectal cancer patients taking angiotensin-converting enzyme inhibitors or angiotensin receptor blockers.

BACKGROUND: Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) are commonly used antihypertensive medications that have been reported to affect aberrant angiogenesis and the dysregulated inflammatory response. Because of such mechanisms, it was hypothesized that these medications might affect the tumor response to neoadjuvant radiation in patients with rectal cancer. METHODS: One hundred fifteen patients who were treated with neoadjuvant radiation at the University of Wisconsin (UW) between 1999 and 2012 were identified. Univariate analyses were performed with anonymized patient data. In a second independent data set, 186 patients with rectal cancer who were treated with neoadjuvant radiation at the Queen's Medical Center of the University of Hawaii (UH) between 1995 and 2010 were identified. These data were independently analyzed as before. Multivariate analyses were performed with aggregate data. RESULTS: Among patients taking ACEIs/ARBs in the UW data set, a significant 3-fold increase in the rate of pathologic complete response (pCR) to neoadjuvant therapy (52% vs 17%, P = .001) was observed. This finding was confirmed in the UH data set, in which a significant 2-fold-increased pCR rate (24% vs 12%, P = .03) was observed. Identified patient and treatment characteristics were otherwise balanced between patients taking and not taking ACEIs/ARBs. No significant effect was observed on pCR rates with other medications, including statins, metformin, and aspirin. Multivariate analyses of aggregate data identified ACEI/ARB use as a strong predictor of pCR (odds ratio, 4.02; 95% confidence interval, 2.06-7.82; P < .001). CONCLUSIONS: The incidental use of ACEIs/ARBs among patients with rectal cancer is associated with a significantly increased rate of pCR after neoadjuvant treatment. Cancer 2016;122:2487-95. © 2016 American Cancer Society.