76 Background: Ultra-hypofractionated radiotherapy delivered using stereotactic body radiotherapy (SBRT) is a cost-effective treatment for localized prostate cancer. Optimal dosing remains unclear, as commonly used 30-40Gy/5fx regimens appear to overestimate hypofractionation’s control benefits. Here, we report the largest experience of 45Gy/5Fx of SBRT for prostate cancer patients treated with hydrogel peri-rectal spacer (‘hydrogel’). Methods: An IRB-approved retrospective protocol was used to conduct a registry search identifying all patients with prostate cancer who received 45Gy/5Fx between 2015-2019 with hydrogel. Genitourinary (GU) and gastrointestinal (GI) toxicities were defined using the NCI Common Toxicity Criteria for Adverse Events (CTCAE) v.5.0. The ASTRO-Phoenix failure definition of Nadir+2 ng/mL was used for biochemical failure. Results: We analyzed 250 low (9.2%), intermediate (85.2%), and high-risk (5.6%) prostate cancer patients with a median follow-up of 9.9 months (range: 0-45.7 months). Acute GU and GI grade ≥ II toxicities were noted in 15.2% and 7.2% of patients, respectively. Late GU grade II and III toxicities occurred in 24.0% and 1.2% of patients, respectively, while late GI grade II and III toxicities occurred in 4.0% and 0.4% of patients, respectively. In patients (N=44) with follow-up >2 years, late GU and GI grade III toxicities occurred in 4.55% and 2.27% of patients, respectively. A significant correlation was noted for acute GI and GU toxicity predicting the respective late GI and GU toxicity (p-value < 0.001 for both). Physician-reported Grade ≥ II new onset erectile dysfunction was 17.2%. A gradual decline in prostate-specific antigen with a mean nadir of 0.04 (95% CI: [0.018, 0.067]) at 36 months was noted. The actuarial freedom from biochemical failure was 96.33% at 3 years. Overall survival was 94.09% at 3 years with no deaths attributed to prostate cancer. Conclusions: SBRT treatment of 45Gy/5Fx with hydrogel is well tolerated with GU/GI toxicities comparable to those reported for conventional fractionation. Although short, the 3-year biochemical control rate is encouraging. Longer follow-up and prospective evaluation are warranted.

PurposeStereotactic ablative radiation (SAbR) has been increasingly used in prostate cancer (PCa) given its convenience and cost efficacy. Optimal doses remain poorly defined with limited prospective comparative trials and long-term safety/efficacy data at higher dose levels. We analyzed toxicity and outcomes for SAbR in men with localized PCa at escalated 45 Gy in 5 fractions.Methods and MaterialsThis study retrospectively analyzed men from 2015 to 2019 with PCa who received linear-accelerator-based SAbR to 45 Gy in 5 fractions, along with perirectal hydrogel spacer, fiducial placement, and MRI-based planning. Disease control outcomes were calculated from end of treatment. Minimally important difference (MID) assessing patient-reported quality of life was defined as greater than a one-half standard deviation increase in American Urological Association (AUA) symptom score after SAbR.ResultsTwo-hundred and forty-nine (249) low-, intermediate-, and high-risk PCa patients with median follow-up of 14.9 months for clinical toxicity were included. Acute urinary grade II toxicity occurred in 20.4% of patients. Acute grade II GI toxicity occurred in 7.3% of patients. For follow-up &gt; 2 years (n = 69), late GU and GI grade ≥III toxicity occurred in 5.8% and 1.5% of patients, respectively. MID was evident in 31.8%, 23.4%, 35.8%, 37.0%, 33.3%, and 26.7% of patients at 3, 6, 12, 24, 36, and 48 months, respectively. The median follow-up for biochemical recurrence was 22.6 months with biochemical failure-free survival of 100% at 1 year (n = 226) and 98.7% for years 2 (n = 113) and 3 (n = 54).ConclusionsSAbR for PCa at 45 Gy in 5 fractions shows an encouraging safety profile. Prospective studies with longer follow-up are warranted to establish this dose regimen as standard of care for PCa.

INTRODUCTION: Rocky Mountain spotted fever (RMSF), a tick-borne illness, and a Spotted fever Rickettsiosis, presents with nonspecific symptoms (e.g., high fever, headache, myalgia) with a high mortality rate in the pre-antibiotic era (20-80%) (1,2). We present a patient who developed thrombotic thrombocytopenic purpura (TTP) with a high PLASMIC SCORE: 6 points. CASE PRESENTATION:A 47-year-old male with no significant past medical history presented to the hospital with altered mental status. His brother reported that the patient's symptoms started 10 days before presentation when the patient chills and shivering. He continued with chills and subsequently developed a severe headache and subsequently reported chest pain, abdominal pain. Physical exam revealed jaundice with scleral icterus. However, with no presence of a rash. The patient lives in a rural area where stray cats, dogs, and cattle were common and allowed inside the house.bLaboratories revealed a white blood cell count (WBC) of 15.4Â 109/L, hemoglobin of 13.4 g/dl, and a platelet count of 20 Â 109/L. A peripheral smear taken upon admission was unremarkable and no evidence of microangiopathic hemolytic anemia. A subsequent peripheral smear showed revealed MAHA with marked thrombocytopenia. The result of immunofluorescence antibody testing for rickettsia immunoglobulin G and M was strongly positive for Rocky Mountain Spotted fever and Flea-borne (murine) typhus.Our patient was treated with doxycycline and admitted to the ICU due to severe illness. Throughout hospitalization, the patient continued to improve, his peripheral smear showed complete resolution of features of disseminated intravascular coagulation and was discharged after 4 days with a course of oral doxycycline DISCUSSION: Rocky Mountain Spotted Fever is an infectious diseasecaused by Rickettsia ricketsii. Tickborne rickettsial diseases in the United States have continued to rise, resulting in severe illness and death in individuals with no prior comorbid conditions, despite the widely available and effective antibacterial therapy. The early signs of tickborne rickettsial illnesses present with nonspecific symptoms; therefore, RMSF can oftentimes be misdiagnosed as an acute viral syndrome, or in our case, as TTP (3). Furthermore, while this disease is often associated with the classic triad of fever, rash, and reported tick bite, only a minority of cases present with these as the initial presentation of symptoms. Clinicians should include rickettsial infection as a diagnostic workup of any patient who presents with a classic pentad of thrombotic thrombocytopenic purpura (TTP).CONCLUSIONS: This case illustrates the importance of rickettsial infections as a differential diagnosis for patients who present with nonspecific febrile illness. With the delay of treatment, this infection can progress rapidly to neurologic manifestations, renal failure, thrombocytopenia, and death.