Higher radiotherapy doses may extend survival in pancreatic cancer

Higher doses of radiotherapy may prolong survival for patients with early-stage pancreatic cancer, according to study results presented at ESTRO 36, the meeting of the European Society for Radiotherapy and Oncology.

“Previous research has not shown a benefit for treating pancreatic cancer with radiotherapy, suggesting that these tumors are somehow resistant to radiation, but this study suggests the situation is more nuanced,” Francesco Cellini, MD, radiation oncologist at Fondazione Policlinico Universitario Agostino Gemelli and Università Cattolica del Sacro Cuore in Rome, said in a press release. “We have found that the higher the dose, the longer the patient is likely to survive. This may indicate that the doses were simply not high enough in previous research.”

An estimated 338,000 people worldwide have pancreatic cancer, and more effective treatments are urgently needed to improve outcomes.

Cellini and colleagues retrospectively analyzed 514 patients from the United States and Europe with early-stage pancreatic cancer. All patients received adjuvant chemotherapy and radiotherapy.

Researchers excluded patients with metastatic or unresectable disease, those who received intraoperative radiotherapy, patients with macroscopic residual disease, those who died within 60 days after surgery, and patients with histological diagnosis different from ductal carcinoma.

Researchers divided qualifying patients into four groups based on radiotherapy dose received (group 1, < 45 Gy; group 2, 45 Gy to < 50 Gy; group 3, 50 Gy to < 55 Gy; and group 4, 55 Gy).

Median follow-up was 20 months. Study results indicated higher radiotherapy doses may be linked with longer survival.

Patients in group 4 achieved the longest median OS (28 months), followed by those in group 3 (22 months), those in group 2 (21 months) and those in group 1 (13 months; P = .004).

Multivariate analysis confirmed a significant association between higher dose and longer survival (HR = 0.46; 95% CI, 0.27-0.78).

“Radiotherapy has benefitted from a number of technological improvements over recent years, and it is becoming easier to give higher doses that are targeted to the tumor area,” Cellini said in the release. “This study suggests radiotherapy should be considered for patients with early-stage pancreatic cancer. It may also be worthwhile to investigate whether current radiotherapy techniques could also bring survival benefits to patients with more advanced tumors.”

Univariate analysis showed shorter OS among patients with higher Ca 19.9 levels (> 90 U/ml, P < .001), higher tumor grade (grade 3 to grade 4, P = .004), those who underwent R1 resection (P = .004), patients with higher primary tumor stage (T3 to T4, P = .002) and those with positive nodes (P < .001).

The study raises questions about the role radiotherapy could play in extending survival for patients with pancreatic cancer, according to Professor Yolande Lievens, head of the department of radiation oncology at Ghent University Hospital in Belgium and president of ESTRO.

“In this grim disease, radiotherapy has not been shown to have an impact on survival, but the current study suggests the doses previously tested may have been too low to do so,” Lievens, who was not involved in the study, said in a press release. “Radiotherapy has evolved and improved considerably over recent years, allowing us to deliver higher doses without increasing side effects and, for a cancer with such poor survival rates, all promising new options should be explored.”

Cellini and colleagues are working on a study to assess the combination of high-dose radiotherapy plus chemotherapy as neoadjuvant treatment for pancreatic cancer. – by Kyle Doherty

Reference:

Morganti AG, et al. Abstract E36-1235. Presented at: ESTRO 36; May 5-9, 2017; Vienna, Austria.