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By Charles Bankhead, Staff Writer, MedPage Today Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner
Discussant: Ted Hong, MD Action Points Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal. Stereotactic ablative radiation (SABR) following chemotherapy allowed 40% of patients with inoperable pancreatic cancer to proceed to surgery, which left no residual disease in 92% of cases. Note that the chemotherapy addresses microscopic disease, which often accompanies locally advanced pancreatic cancer, and SABR, an advanced form of radiation therapy, shrinks the tumor to make surgery more feasible. SAN FRANCISCO -- Stereotactic ablative radiation (SABR) allowed 40% of patients with inoperable pancreatic cancer to proceed to surgery, which left no residual disease in 92% of cases, interim results from a small clinical study showed.
The study involved 34 patients with borderline or locally advanced pancreatic cancer, most of whom would not have undergone surgery or had a high likelihood of unsuccessful surgery. All but three completed a course of combination chemotherapy, followed by SABR.
The chemotherapy addresses microscopic disease, which often accompanies locally advanced pancreatic cancer, and SABR shrinks the tumor to make surgery more feasible, Kimmen Quan, MD, of the University of Pittsburgh, said here at the American Society for Radiation Oncology meeting.
'Neoadjuvant chemotherapy followed by radiosurgery is an attractive treatment option with very low toxicity,' said Quan. 'We were able to address potential micrometastatic disease early, and we were able to deliver a potent radiation dose, which maximizes the potential for a curative resection.
'In the future we will be looking at more active forms of chemotherapy such as FOLFIRINOX [folinic acid + fluorouracil + irinotecan + oxaliplatin], followed by the same paradigm of radiosurgery and surgery for these patients.'
An advanced form of radiation therapy, SABR facilitates delivery of a higher radiation dose to a disease target with increased precision for avoiding adjacent healthy tissue. The technique has considerable promise for locally advanced pancreatic cancer and other malignancies that are often difficult or impossible to treat by surgery, which may offer the best chance for disease control or a cure, said Quan.
The study population considvanced disease. Treatment began with four cycles of induction chemotherapy with gemcitabine and capecitabine. All but three patients completed the full course of chemotherapy, as one patient died after giving consent and two others died of thromboembolic events during chemotherapy.
The 31 patients who completed chemotherapy also completed the SABR protocol, which consisted of 36 Gy delivered in three fractions to the planning target volume (PTV), which averaged 24.3 cm3. After restaging, 12 of the 31 (40%) patients underwent surgery (10 patients with borderline resectable disease and two with locally advanced). Surgery led to R0 postoperative status in 11 of 12 patients, as one of the patients with locally advanced disease had residual tumor after surgery.
One patient had grade 3 gastrointestinal toxicity during chemotherapy, three patients had grade 3 hematologic toxicities, and one had grade 4 hematologic toxicity. Additionally, two patients had grade 3 postoperative adverse events (pseudoaneurysm and hepatic abscess) and two had grade 4 postoperative events (ICU admission for cerebrovascular accident and portal vein thrombosis). SABR was not associated with acute toxicity.
Among 20 patients with pre-chemotherapy and post-SABR measures of the tumor marker CA19-9, the mean value declined from 867 prior to chemotherapy to 177 after SABR (P=0.009). Quan acknowledged that a normal CA19-9 level would be less than 37. Quality-of-life assessments suggested that the treatment did not negatively affect patients' overall health status or functional ability.
Patients who had borderline resectable disease at enrollment had a 1-year local progression-free survival (LPFS) of 86% and a 25.5-month median disease-free survival (DFS). Among the patients with locally advanced disease, the 1-year LPFS was 100%, and median DFS was 22.5 months.
The study reflects an evolving trend toward development of highly focused, short-course radiation therapy regimens to combine with chemotherapy and enable more patients with inoperable or borderline pancreatic cancer to proceed to surgery and a potential cure, said press briefing moderator Theodore DeWeese, MD, of Johns Hopkins.
'This study shows that radiation can be delivered in a much more conformal manner that leads to fewer side effects and can be done in a less time-consuming fashion, which obviously increases quality of life for patients,' said DeWeese.
In response to a question, DeWeese pointed out that the regimen is applicable to the vast majority of patients with newly diagnosed pancreatic cancer, about 80% of whom have locally advanced or borderline disease and 20% have diagnoses that occur while the disease is still resectable.
For some time, pancreatic cancer specialists have been moving toward multimodality therapy that includes focused radiation therapy as a means of improving the proportion of patients who can undergo surgery, said Ted Hong, MD, of Massachusetts General Hospital in Boston. The 40% resectability rate is an improvement over rates seen in the past with older forms of therapy but is in keeping with what many other centers are obtaining with chemotherapy and SABR.
'I think they will see the resection rate increase even further when they use more contemporary chemotherapy regimens,' Hong told MedPage Today. 'We have been using FOLFIRINOX for awhile, as have others, and resection rates as high as 80% are not uncommon.'
Quan disclosed no relevant relationships with industry.
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