Consolidatory ablative stereotactic body radiation therapy after induction chemotherapy for unresectable pancreatic cancer: A single center experience

Background and purpose

Consolidatory radiotherapy in form of stereotactic body radiation therapy (SBRT) with an ablative dose following induction chemotherapy is emerging as a promising treatment scheme for unresectable pancreatic cancer. Outcomes of given treatment at a single center for contiguous patients with unresectable pancreatic cancer were evaluated to build the optimal treatment strategy.

Materials and methods

In this retrospective study, a total of 50 patients with unresectable pancreatic cancer who underwent induction chemotherapy and ablative dose SBRT were included. SBRT dose was 40-50 Gy in five fractions. Two strategies were adopted to adhere to the organs at risk (OAR) dose constraints: simultaneous integrated protection (SIP) technique and magnetic resonance (MR)-guided adaptive technique. Overall survival (OS) and local progression-free survival (LPFS) were calculated from the start date of SBRT.

Results

The median follow-up period for survivors was 21.1 months (range, 6.2-61.0 months). Eleven (22.0%) patients underwent resection after SBRT, which were all R0 resection. In patients with non-metastatic disease, the median OS was 26.5 months (range, 4.1-61.0 months), and the 1- and 3-year LPFS were 90.0% (95% confidence interval [CI], 72.0-96.7%) and 57.4% (95% CI, 31.7-76.4%), respectively. Patients with oligometastatic disease had inferior survival outcomes, but there was no survival difference among responders to induction chemotherapy. In the multivariable analysis, tumor size ≤4 cm, non-metastatic status, and good response to induction chemotherapy were associated with improved LPFS. In dosimetric analysis, GTV Dmin ≥50.5 Gy was the strongest prognosticator against local progression. Grade ≥3 adverse events occurred in two (4.0%) patients with non-adaptive RT, but none in patients with MR-guided adaptive RT.

Conclusion

Ablative dose SBRT following induction chemotherapy is an effective strategy for selected patients with unresectable pancreatic cancer. The SIP technique and MR-guided adaptive RT were attributed to minimizing the risk of adverse events. Further studies are needed to identify the best candidates for consolidatory SBRT in unresectable pancreatic cancer.

Hypofractionated radiotherapy for hepatocellular carcinomas adjacent to the gastrointestinal tract

AIM

Decisions regarding therapeutic plans for inoperable patients with hepatocellular carcinoma (HCC) adjacent to the gastrointestinal (GI) tract are challenging because radiofrequency ablation has the potential risk of thermal injury. Moreover, the response rate of transcatheter arterial chemoembolization is relatively low and stereotactic body radiotherapy (SBRT) is believed to be too toxic. We have applied hypofractionated radiotherapy (HFRT) for such lesions. This study investigated the outcomes and toxicities of this treatment.

METHODS

Among consecutive HCC patients treated with radiotherapy with curative intent at our institution between 2015 and 2019, we retrospectively extracted those outside of the indication for SBRT due to exceeding the constraint of the GI tract and who were treated using HFRT with a prescription dose of 42 Gy in 14 fractions and prophylactic proton pump inhibitor administration for 6 months. The oncological outcomes and toxicities were investigated.

RESULTS

A total of 66 patients with 73 lesions were eligible. The median follow-up period was 24.0 months. The local recurrence, intrahepatic recurrence, liver-related death, and overall survival rates at 2 years were 11.3%, 50.6%, 15.9%, and 60.4%, respectively. Six (9.1%) patients experienced Child-Pugh score deterioration ≥2 within 6 months following treatment. Two and one patient developed grades 2 and 3 gastroduodenal bleeding, respectively.

CONCLUSIONS

HFRT can achieve good local control in patients with HCC adjacent to the GI tract, with low GI toxicity incidence. Our study demonstrated that HFRT can be a potentially curative treatment option for lesions.