Jörg Kleef and colleagues systematically reviewed studies on neoadjuvant therapy and tumor response, toxicity, resection, and survival percentages in pancreatic cancer and suggest that patients with locally nonresectable tumors should be included in neoadjuvant protocols.
Pancreatic cancer has an extremely poor prognosis and prolonged survival is achieved only by resection with macroscopic tumor clearance. There is a strong rationale for a neoadjuvant approach, since a relevant percentage of pancreatic cancer patients present with non-metastatic but locally advanced disease and microscopic incomplete resections are common. The objective of the present analysis was to systematically review studies concerning the effects of neoadjuvant therapy on tumor response, toxicity, resection, and survival percentages in pancreatic cancer.
Methods and Findings
Trials were identified by searching MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials from 1966 to December 2009 as well as through reference lists of articles and proceedings of major meetings. Retrospective and prospective studies analyzing neoadjuvant radiochemotherapy, radiotherapy, or chemotherapy of pancreatic cancer patients, followed by re-staging, and surgical exploration/resection were included. Two reviewers independently extracted data and assessed study quality. Pooled relative risks and 95% confidence intervals were calculated using random-effects models. Primary outcome measures were proportions of tumor response categories and percentages of exploration and resection. A total of 111 studies (n = 4,394) including 56 phase I–II trials were analyzed. A median of 31 (interquartile range [IQR] 19–46) patients per study were included. Studies were subdivided into surveys considering initially resectable tumors (group 1) and initially non-resectable (borderline resectable/unresectable) tumors (group 2). Neoadjuvant chemotherapy was given in 96.4% of the studies with the main agents gemcitabine, 5-FU (and oral analogues), mitomycin C, and platinum compounds. Neoadjuvant radiotherapy was applied in 93.7% of the studies with doses ranging from 24 to 63 Gy. Averaged complete/partial response probabilities were 3.6% (95% CI 2%–5.5%)/30.6% (95% CI 20.7%–41.4%) and 4.8% (95% CI 3.5%–6.4%)/30.2% (95% CI 24.5%–36.3%) for groups 1 and 2, respectively; whereas progressive disease fraction was estimated to 20.9% (95% CI 16.9%–25.3%) and 20.8% (95% CI 14.5%–27.8%). In group 1, resectability was estimated to 73.6% (95% CI 65.9%–80.6%) compared to 33.2% (95% CI 25.8%–41.1%) in group 2. Higher resection-associated morbidity and mortality rates were observed in group 2 versus group 1 (26.7%, 95% CI 20.7%–33.3% versus 39.1%, 95% CI 29.5%–49.1%; and 3.9%, 95% CI 2.2%–6% versus 7.1%, 95% CI 5.1%–9.5%). Combination chemotherapies resulted in higher estimated response and resection probabilities for patients with initially non-resectable tumors (“non-resectable tumor patients”) compared to monotherapy. Estimated median survival following resection was 23.3 (range 12–54) mo for group 1 and 20.5 (range 9–62) mo for group 2 patients.
In patients with initially resectable tumors (“resectable tumor patients”), resection frequencies and survival after neoadjuvant therapy are similar to those of patients with primarily resected tumors and adjuvant therapy. Approximately one-third of initially staged non-resectable tumor patients would be expected to have resectable tumors following neoadjuvant therapy, with comparable survival as initially resectable tumor patients. Thus, patients with locally non-resectable tumors should be included in neoadjuvant protocols and subsequently re-evaluated for resection.
Please see later in the article for the Editors' Summary
Pancreatic cancer is the fourth leading cause of cancer-related deaths worldwide. It begins when a cell in the pancreas (an organ lying behind the stomach that produces digestive enzymes and hormones such as insulin that controls blood sugar levels) acquires genetic changes that allow it to grow uncontrollably and, sometimes, to spread around the body (metastasize). Because pancreatic cancer rarely causes any symptoms early in its development, it is locally advanced in more than a third of patients and has already metastasized in another half of patients by the time it is diagnosed. Consequently, on average, people die within 5–8 months of a diagnosis of pancreatic cancer. At present, the only chance for cure is surgical removal (resection) of the tumor, part of the pancreas, and other nearby digestive organs. This procedure—the Whipple procedure—is only possible in the fifth of patients whose tumor is found when it is small enough to be resectable, and even in these patients, the cure rate associated with surgery is less than 25%, although radiotherapy or chemotherapy after surgery (adjuvant therapy) can be beneficial.
Why Was This Study Done?
For patients whose tumor has metastasized, palliative chemotherapy to slow down tumor growth and to minimize pain is the only treatment option. But, for the many patients whose disease is locally advanced and unresectable at diagnosis, experts think that “neoadjuvant” therapy might be helpful. Neoadjuvant therapy—chemotherapy and/or radiotherapy given before surgery—aims to convert unresectable tumors into resectable tumors by shrinking the visible tumor and removing cancer cells that cannot be seen with the naked eye. Randomized phase III trials—studies in which groups of patients are randomly assigned to different interventions and specific outcomes measured—are the best way to determine whether an intervention has any clinical benefits, but no randomized phase III trials of neoadjuvant therapy for unresectable pancreatic cancer have been undertaken. Therefore, in this systematic review (a study that uses predefined criteria to identify all the research on a given topic) and meta-analysis (a statistical method for combining the results of several studies), the researchers analyze data from other types of studies to investigate whether neoadjuvant therapy for pancreatic cancer provides any clinical benefits.
What Did the Researchers Do and Find?
In their systematic review, the researchers identified 111 studies involving 4,394 patients in which the effects of neoadjuvant chemotherapy and/or radiotherapy on tumor response, tumor resectability, and patient survival had been investigated. They subdivided the studies into two groups: group 1 studies included patients whose tumors were considered resectable on preoperative examination, and group 2 studies included patients whose tumors were borderline resectable or unresectable. In their meta-analysis, the researchers found that similar percentages of the tumors in both groups responded to neoadjuvant therapy by shrinking or regressing and that about a fifth of the tumors in each group grew larger or metastasized during neoadjuvant therapy. In the group 1 studies, three-quarters of the tumors were resectable after neoadjuvant therapy (a decrease in the proportion of tumors that could be treated surgically) whereas in the group 2 studies, a third of the tumors were resectable after neoadjuvant therapy (an increase in the proportion of tumors that could be treated surgically). After resection, the average survival time for group 1 patients was 23.3 months, a similar survival time to that seen in patients treated with surgery and adjuvant therapy. The average survival time for group 2 patients after resection was 20.5 months.
What Do These Findings Mean?
The finding that the average survival time after neoadjuvant therapy and surgery in patients whose tumor was judged resectable before neoadjuvant therapy was similar to that of patients treated with chemotherapy and/or radiotherapy after surgery suggests that for patients with resectable tumors, neoadjuvant therapy will not provide any clinical benefit. By contrast, the finding that a third of patients initially judged unresectable were able to undergo resection after neoadjuvant therapy and then had a similar survival rate to patients judged resectable before neoadjuvant treatment strongly suggests that patients presenting with locally advanced/unresectable tumors should be offered neoadjuvant therapy and then re-evaluated for resection. Randomized trials are now needed to confirm this finding and to determine the optimum neoadjuvant therapy for this group of patients.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1000267.
The US National Cancer Institute provides information for patients and health professionals about all aspects of pancreatic cancer (in English and Spanish), including a booklet for patients
The American Cancer Society also provides detailed information about pancreatic cancer
The UK National Health Service and Cancer Research UK include information for patients on pancreatic cancer on their Web sites
MedlinePlus provides links to further resources on pancreatic cancer (in English and Spanish)
Pancreatica.org, PancreaticDuct.org, and the Pancreatic Cancer Action Network give more information to pancreatic cancer patients, their families, and caregivers