Hypofractionated Intensity Modulated Proton Therapy (IMPT) and Systemic Therapy for Unresectable Hepatobiliary Cancers

PURPOSE/OBJECTIVE(S)

Proton therapy offers significantly reduced normal liver dose compared to photon therapy for liver tumors, and therefore has the potential for dose escalation and hypofractionation. Employing IMPT, we have initiated a hypofractionated treatment regimen for unresectable liver cancer at a single academic institution. Here we report our initial results on dosimetry and clinical outcomes of hypofractionated IMPT for unresectable hepatocellular carcinoma (HCC) and cholangiocarcomas (CC).

MATERIALS/METHODS

We retrospectively reviewed records of consecutive patients treated with IMPT for CC and HCC from 2018 to 2021. Inverse treatment planning with robust optimization, daily image guidance, pencil beam scanning dose delivery were used for all patients. Motion management included 4D-CT and abdominal compression. Toxicity was graded using the Common Terminology Criteria for Adverse Events version 5.0 and survival was calculated using the Kaplan Meier method.

RESULTS

We identified 15 patients (3 HCC, 4 intrahepatic CC, 8 hilar CC) treated with IMPT to a median dose of 5805 cGy (range, 4500 - 6000 cGy) in 15 fractions. Two had metastatic and 13 had regional disease. Median tumor volume was 91.5 cc (range, 10.92 - 366.31 cc). Prior therapies included: 12 patients received upfront chemotherapy, (gemcitabine plus cisplatin most common), 4 received prior surgery on the liver, and 5 received prior liver directed treatment. With a median follow up of 10 months, the median overall survival (OS) and 1-year OS was 18.7 months and 76% respectively. One patient underwent resection and 1 patient received liver transplant; 7 (47%) patients had disease progression (3 local, 1 regional lymph node, 4 elsewhere liver, 5 distant metastatic). Five patients with CC developed grade 3 toxicity in the form of cholangitis (4) and hemobilia (1). Of these patients, 4 patients were of the hilar type.

CONCLUSION

Our early results using hypofractionated IMPT for unresectable HCC and CC resulted in encouraging local control rates with an acceptable toxicity profile. Further study is warranted to determine the optimal liver directed therapy for this challenging patient population.

Safety of stereotactic body radiation therapy for localized prostate cancer without treatment planning MRI

Background

The use of treatment planning prostate MRI for Stereotactic Body Radiation Therapy (SBRT) is largely a standard, yet not all patients can receive MRI for a variety of clinical reasons. Thus, we aim to investigate the safety of patients who received CT alone based SBRT planning for the definitive treatment of localized prostate cancer.

Methods

Our study analyzed 3410 patients with localized prostate cancer who were treated with SBRT at a single academic institution between 2006 and 2020. Acute and late toxicity was evaluated using the Common Terminology Criteria for Adverse Events version 5.0. Expanded Prostate Cancer Index Composite (EPIC) questionnaires evaluated QOL and PSA nadir was evaluated to detect biochemical failures.

Results

A total of 162 patients (4.75%) received CT alone for treatment planning. The CT alone group was older relative to the MRI group (69.9 vs 67.2, p < 0.001) and had higher risk and grade disease (p < 0.001). Additionally, the CT group exhibited a trend in larger CTVs (82.56 cc vs 76.90 cc; p = 0.055), lower total radiation doses (p = 0.048), and more frequent pelvic nodal radiation versus the MRI group (p < 0.001). There were only two reported cases of Grade 3 + toxicity within the CT alone group. Quality of life data within the CT alone group revealed declines in urinary and bowel scores at one month with return to baseline at subsequent follow up. Early biochemical failure data at median time of 2.3 years revealed five failures by Phoenix definition.

Conclusions

While clinical differences existed between the MRI and CT alone group, we observed tolerable toxicity profiles in the CT alone cohort, which was further supported by EPIC questionnaire data. The overall clinical outcomes appear comparable in patients unable to receive MRI for their SBRT treatment plan with early clinical follow up.