Predictive Value of Tumor Volume on Local Control in Hepatocellular Carcinoma Treated with Image Guided Hypofractionated Radiation Treatment

PURPOSE/OBJECTIVE(S)

External beam radiation treatment (EBRT) is an important local treatment in liver-confined hepatocellular carcinoma (HCC) patients who are not candidates for curative therapy. EBRT dose, technique and prognostic factors are evolving. We hypothesized that tumor volume to liver volume ratio can be a predictor of local control (LC) in patients treated with hypo-fractionated radiation (HFRT) in HCC MATERIALS/METHODS: We retrospectively reviewed 50 patients of HCC treated with HFRT at our institution. HFRT schedule was chosen such that the radiation dose to the remaining liver and other organs at risk (OAR) met the standard dosimetric constraints. Image guided techniques were used for motion management, internal target volume (ITV) and planning target volume (PTV) delineation. Tumor to Liver Ratio (TLR) was defined as ratio of PTV volume to whole liver volume. TLR ≤ 0.3 was considered as low volume disease and TLR > 0.3 was considered as high-volume disease. The radiation dose ranged from 45 Gy to 67.5 Gy in 5 - 15 fractions. The biologically equivalent dose (BED) for tumor ranged from 58.5 Gy10 to 100 Gy10. Local control (LC) was evaluated by Kaplan-Meier analysis, with log-rank test for groups stratified as per TLR. Multivariate Cox regression analysis was performed to identify additional prognostic factors.

RESULTS

The mean duration of follow-up was 24 months. The median age was 69 years (range 50 - 90) and 76% were males. 32 patients had CP-A class cirrhosis while 17 had CP-B and 1 had CP-C class. BCLC stage A, B, C and D was seen in 2, 14, 33 and 2 patients, respectively. Portal vein thrombosis was present in 9 patients and prior trans-arterial chemo embolization (TACE) was done in 23 patients. The median volume of PTV was 551 cc (range 52 - 1990 cc). The TLR ranged from 0.04 - 0.67 with a median of 0.29. The median BED radiation dose was 78.4 Gy10 (range - 58.5 Gy10 to 100 Gy10). Nine patients had local recurrence with overall LC rate of 82%. The LC was better in low volume tumors, with the TLR cut-off of 0.3 as a significant factor associated with LC (p = 0.007). The 1-year actuarial LC with TLR ≤ 0.3 was 88% as compared 61% in TLR of > 0.3 (p = 0.007). BED ≥60 Gy10 was associated with better 1 year LC as compared to BED < 60 Gy10 (89% vs 62%; p = 0.11). ALBI grade 1 was associated with better 1 year LC as compared to ALBI grade 2 (80% versus 75%; p = 0.40). On multivariate analysis, high volume disease and TLR >0.3 were significant prognostic factor for LC.

CONCLUSION

HFRT has good 1-year local control of 82% in carefully selected unresectable HCC. Radiation with BED greater than 60 Gy10 and ALBI grade 1 showed a trend towards better LC. Smaller tumors had better LC with a PTV to liver ratio (TLR) of < 0.3. This information can help in identifying the poor responders, intensifying the radiation treatment and adding additional therapy to improve the oncological outcomes.

A Single-Institution Experience of Acute Neuropathic Lumbosacral Pain in Patients Treated with Short Course Hypofractionated Radiotherapy in Locally Advanced Rectal Cancer

PURPOSE/OBJECTIVE(S)

There has been increased interest in the use of short course hypofractionated radiotherapy as part of a total neoadjuvant treatment (TNT) approach in the management of rectal cancer since publication of the RAPIDO trial. However, the literature on short course radiation for rectal cancer has not reported significant acute toxicities in the weeks immediately following the completion of treatment. Anecdotally, a subset of patients has experienced acute neuropathic pain characterized in a lumbosacral distribution. This study investigates acute lumbosacral toxicity for patients receiving hypofractionated short course radiation as part of their definitive treatment for rectal cancer.

MATERIALS/METHODS

We retrospectively analyzed 75 patients with locally advanced rectal adenocarcinoma treated with hypofractionated short course radiation (25 Gy in 5 fractions) at our institution between 2016 and 2022. Acute toxicity caused by radiation was defined as that occurring from the start of radiation treatment to either 30 days post radiation completion, the start of chemotherapy, or date of surgery, whichever occurred first.

RESULTS

Among 75 patients treated with hypofractionated short course preoperative radiation with definitive intent, we identified 10 patients (13.3%) who experienced significant lumbosacral neuropathic pain and initiated a report to their medical providers during the acute toxicity time frame. Commonly, this was described as an achy pain in the bilateral buttocks radiating down to the knees or posterior claves. Patients rated this pain between moderate to extreme and management included steroids after failure of improvement with conservative measures, gabapentin, and conservative treatment with NSAIDs and Tylenol. Average time to onset of acute lumbosacral neuropathic pain was 3.7 days (SD 2.05) from start of RT.

CONCLUSION

We have identified a previously underappreciated acute toxicity of neuropathic lumbosacral pain in short course hypofractionated radiation therapy, which may be due to a lumbosacral plexus toxicity. Further analysis will seek to identify predictive factors such as comorbidities and dose to the lumbosacral plexus, and to determine whether there is a correlation between these observed acute toxicities and long-term outcomes.

Temporary inhibition of the plasminogen activator inhibits periosteal chondrogenesis and promotes periosteal osteogenesis during appendicular bone fracture healing

INTRODUCTION

Aminocaproic acid is approved as an anti-fibrinolytic for use in joint replacement and spinal fusion surgeries to limit perioperative blood loss. Previous animal studies have demonstrated a pro-osteogenic effect of aminocaproic acid in spine fusion models. Here, we tested if aminocaproic acid enhances appendicular bone healing and we sought to uncover the effect of aminocaproic acid on osteoprogenitor cells (OPCs) during bone regeneration.

METHODS

We employed a well-established murine femur fracture model in adult C57BL/6J mice after receiving two peri-operative injections of aminocaproic acid. Routine histological assays, biomechanical testing and micro-CT analyses were utilized to assess callus volume, and strength, progenitor cell proliferation, differentiation, and remodeling in vivo. Two disparate ectopic transplantation models were used to study the effect of the growth factor milieu within the early fracture hematoma on osteoprogenitor cell fate decisions.

RESULTS

Aminocaproic acid treated femur fractures healed with a significantly smaller cartilaginous callus, and this effect was also observed in the ectopic transplantation assays. We hypothesized that aminocaproic acid treatment resulted in a stabilization of the early fracture hematoma, leading to a change in the growth factor milieu created by the early hematoma. Gene and protein expression analysis confirmed that aminocaproic acid treatment resulted in an increase in Wnt and BMP signaling and a decrease in TGF-β-signaling, resulting in a shift from chondrogenic to osteogenic differentiation in this model of endochondral bone formation.

CONCLUSION

These experiments demonstrate for the first time that inhibition of the plasminogen activator during fracture healing using aminocaproic acid leads to a change in cell fate decision of periosteal osteoprogenitor cells, with a predominance of osteogenic differentiation, resulting in a larger and stronger bony callus. These findings may offer a promising new use of aminocaproic acid, which is already FDA-approved and offers a very safe risk profile.