Purpose: The oligometastatic state is a proposed entity between localized cancer and widely metastatic disease, comprising an intermediate subset of metastatic cancer patients. Most data to support locally-directed treatment, such as stereotactic ablative radiotherapy (SABR), for oligometastases are from retrospective institutional reports. Following the success of a recently completed and reported phase II trial demonstrating important clinical outcomes, herein we review the current landscape of ongoing clinical trials in this context. Materials and methods: A review of currently activated and registered clinical trials was performed using the clinicaltrials.gov database from inception to February 2019. A search of actively recruiting trials, using the key words oligometastases, SABR, and various related terms was performed. Search results were independently reviewed by two investigators, with discrepancies settled by a third. Data abstracted from identified studies included study type, primary disease site, oncologic endpoints, and inclusion/exclusion criteria. Results: Of the initial 216 entries identified, 64 met our review eligibility criteria after full-text review. The most common study type was a phase II clinical trial (n = 35, 55%) with other study designs ranging from observational registry trials to phase III randomized controlled trials (RCTs). A minority of trials were randomized in design (n = 17, 27%). While most studies allowed for metastases from multiple primary disease sites (n = 22, 34%), the most common was prostate (n = 13, 15%), followed by breast, gastrointestinal, non-small cell lung cancer (NSCLC), and renal (n = 6, 9% each). In studies with a solitary target site, the most common was liver (n = 6, 9%) followed by lung (n = 3, 5%). The most common primary endpoints were progression-free survival (PFS) (n = 20, 31%) and toxicity (n = 10, 16%). A combined strategy of systemic therapy and SABR was an emerging theme (n = 23, 36%), with more recent studies specifically evaluating SABR and immunotherapy (n = 9, 14%). Conclusion: The safety and efficacy of SABR as oligometastasis-directed treatment is increasingly being evaluated within prospective clinical trials. These data are awaited to compliment the abundance of existing observational studies and to guide clinical decision-making.

Artificial intelligence (AI)-based models have become a growing area of interest in predictive medicine and have the potential to aid physician decision-making to improve patient outcomes. Imaging and radiomics play an increasingly important role in these models. This review summarizes recent developments in the field of radiomics for AI in head and neck cancer. Prediction models for oncologic outcomes, treatment toxicity, and pathological findings have all been created. Exploratory studies are promising; however, validation studies that demonstrate consistency, reproducibility, and prognostic impact remain uncommon. Prospective clinical trials with standardized procedures are required for clinical translation.

In this prospective registry we prospectively assessed the oncologic, functional and safety outcomes of salvage high intensity focused ultrasound for radiorecurrent prostate cancer. A total of 81 men were prospectively recruited and evaluated at regular scheduled study visits to 6 months after high intensity focused ultrasound and thereafter as per standard of care. Transrectal ultrasound guided biopsy was performed at 6 months. The primary end point was absence or histological persistence of disease at 6-month biopsy. Secondary end points included quality of life, biochemical recurrence-free survival, overall survival, cancer specific survival and progression to androgen deprivation therapy. Survival analysis was performed according to the Kaplan-Meier method and multivariate analysis was performed using the log rank (Mantel-Cox) test. Mean ± SD prostate specific antigen before high intensity focused ultrasound was 4.06 ± 2.88 ng/ml. At 6 months 63 men underwent biopsy, of whom 22 (35%) had residual disease. At a mean followup of 53.5 ± 31.6 months median biochemical recurrence-free survival was 63 months. The 5-year overall and cancer specific survival rates were 88% and 94.4%, respectively. Nadir prostate specific antigen less than 0.5 ng/ml was a significant predictor of biochemical recurrence-free survival (p=0.014, 95% CI 1.22-5.87). I-PSS significantly increased (p <0.001) while IIEF-5 scores decreased and the SF-36 score did not change significantly. The rate of rectal fistulization and severe incontinence was 3.7% each. A total of 223 complications were recorded in the 180 days after high intensity focused ultrasound (Clavien-Dindo grade 1-195, grade II-20, grade III-7, grade IVa-1). Salvage high intensity focused ultrasound appears to be a viable treatment option for radiorecurrent prostate cancer, with acceptable morbidity.

Management of localized radio-recurrent prostate cancer is not standardized, partly due to the absence of long-term data on oncologic control and the toxicity of various treatment modalities. We analyzed the long-term oncologic outcomes and morbidity of salvage cryoablation for radio-recurrent prostate cancer. Patients undergoing salvage cryoablation for biopsy proven, localized radio-recurrent prostate cancer from 1995 to 2004 were prospectively accrued. Preoperative characteristics, perioperative morbidity and postoperative data were reviewed from a prospectively maintained database or via telephonic contact with the patient. The primary outcome was overall survival. Secondary outcomes were metastasis-free and biochemical disease-free survival. The Kaplan-Meier method was used for survival analysis and multivariable Cox regression analysis was performed. Of 187 patients 157 (84%) had records available for followup. Mean ± SD age was 69.4 ± 5.8 years and mean presalvage prostate specific antigen was 6.6 ± 5.7 ng/ml. Median followup was 117 months (IQR 55–154). Five and 10-year overall survival was 93% and 76%, respectively. Biochemical disease-free survival at 10 and 15 years was 35% and 22.6% whereas metastasis-free survival at 10 and 15 years was 86% and 71%, respectively. On multivariable analysis precryoablation and nadir prostate specific antigen values were significant predictors of metastasis-free and biochemical disease-free survival. Age at salvage cryoablation (p = 0.008) and nadir prostate specific antigen (p = 0.015) were significant predictors of overall survival. There were 157 Clavien-Dindo grade 1-2 and 22 grade 3 complications. A single center, long-term experience documented by a prospectively maintained database shows that cryoablation is a viable salvage option for radio-recurrent prostate cancer as it provides durable biochemical disease-free survival with acceptable morbidity.