NEW PANCREATIC CANCER STAGING

NEW YORK (Reuters Health) - Recent changes in the American Joint Commission on Cancer (AJCC) T and N classification of pancreatic adenocarcinoma provide more reproducible staging, according to a multi-institutional validation study.

The proposed definitions for the AJCC 8th edition would reclassify T as T1 <=2 cm maximal diameter, T2 >2, <=4 cm maximal diameter, T3 >4 cm maximal diameter, and T4 = locally unresectable. Proposed N-stage definitions would include N0 = node negative, N1 = one to three nodes positive for metastatic disease, and N2 >= four nodes positive for metastatic disease.

Dr. Peter J. Allen from Memorial Sloan Kettering Cancer Center in New York City and colleagues evaluated the new proposal versus the current 7th edition in a validation study that included more than 2,300 patients who had undergone pancreatectomy for pancreatic adenocarcinoma.

The new T staging allocated 18% of patients to T1, 22% to T2, and 60% to T3, and recursive partitioning confirmed that this classification was significantly associated with survival.

Positive node cutoff points identified by recursive partitioning also supported the proposed AJCC 8th edition N-staging definitions, according to the new report, online May 9 in Annals of Surgery.

When patients were staged according to this system, 8% had stage IA, 22% had IB, 4% had IIA, 40% had IIB, and 26% had stage III disease, whereas the 7th edition would have classified 68% of patients as stage IIB.

Compared with the 7th edition, within the proposed 8th edition system, there was no longer a majority of patients with N-stage IIB, nor was there a majority in any single-stage stratum. The median survival of N2 patients, now defined as stage 3 disease (along with locally unresectable), was 16.3 months

"The proposed cutoff points for T-stage and N-stage have been found to be statistically valid," the researchers conclude. "Furthermore, the use of tumor diameter alone was shown to be a variable that is more reproducible between institutions and pathologists, and allows for a more even distribution of patients within stage groupings without the sacrifice of prognostic accuracy."

"Although AJCC stage remains one of the strongest predictors of outcome, the concordance probability estimates (CPEs) in this study demonstrate a continued need for improved prognostic tools," they add.

Dr. Allen did not respond to a request for comment.