Major pathologic response to preoperative chemotherapy and radiation occurs in a minority of patients with pancreatic adenocarcinoma and is independently associated with prolonged survival, according to a recent study presented at the 46th annual meeting of the American Society of Clinical Oncology (ASCO) on June 6 in Chicago.
Yun Shin Chun, MD, a surgical oncologist at Fox Chase Cancer Center in Philadelphia and colleagues said that while pathologic response to preoperative therapy is increasingly recognized as an important prognostic factor in solid tumors, the impact of pathologic response on survival in pancreatic adenocarcinoma is not well-established. “Previous studies have shown conflicting results," noted Chun.
Between July 1987 and May 2009, the researchers reviewed data on 135 consecutive patients treated with gemcitabine or 5-fluorouracil-based chemoradiation followed by pancreatectomy for adenocarcinoma of the pancreatic head and/or body.
According to the researchers, prospective histopathologic examination was performed in 108 patients to determine pathologic response, which was classified as minor (less than 50 percent fibrosis relative to residual neoplastic cells), partial (50-94 percent fibrosis) and major (95-100 percent fibrosis).
Chun and colleagues found that 17 percent experienced a minor pathologic response rate to preoperative therapy, 64 percent showed a partial response rate and 19 percent yielded a major response, including a complete pathologic response rate of 7 percent. Pathologic response was correlated with surgical resection, positive lymph nodes and tumor size, wrote the authors.
Median survival rates for those with a minor, partial and major pathological response were 10 months, 14 months and 51 months, respectively, said the researchers, noting that major pathologic response and surgical resection were independent predictors of survival.
While major pathological response to treatments for this type of pancreatic cancer, Chun noted that other studies have pointed to preoperative therapy for various forms of cancer as beneficial and further studies are warranted.
"For many cancers––breast, esophagus, stomach, and colorectal liver metastases––it has been shown that survival is much better in people who have a good pathologic response to preoperative therapy,” said Chun. "Going forward, if we can identify molecular factors in tumors associated with a major pathologic response, then we can make important progress in this disease."