ORLANDO – Patients with stage IA to IIA gastric adenocarcinoma are frequently managed with surgery alone, but a subset of these patients may benefit from adjuvant chemotherapy and/or radiation, suggested Boston-based investigators at a symposium sponsored by the Society of Surgical Oncology.
A review of Surveillance Epidemiology and End Results (SEER) registry data on 8,515 patients treated for gastric adenocarcinoma found that stages, age, tumor differentiation status, tumor size, and location are significantly associated with worse disease-specific survival (DSS) among patients with earlier diseases, reported Dr. Jason S. Gold, chief of surgical oncology at the VA Boston Healthcare System.
Dr. Jason S. Gold
"Patients with at least two of these adverse features had a 5-year disease-specific survival of 76% or less, and perhaps these patients would be benefited by adjuvant treatment," said Dr. Gold.
Although the benefit of adjuvant therapy for stage IIB to IIIC gastric adenocarcinomas has been well documented in randomized trials, there are patients with less advanced-stage disease who have a poor prognosis and might also benefit from adjuvant therapy, Dr. Gold said.
Consensus guideline recommendations on the use of adjuvant therapy vary, with U.S. (National Comprehensive Cancer Network) and Canadian (Cancer Care Ontario) guidelines recommending adjuvant therapy for all patients except those with T1 tumors with no lymph node involvement. In contrast, European guidelines (Norwegian and Dutch) generally recommend adjuvant treatment for cancers with serosal invasion or nodal positivity, but not for patients with T1 tumors and 0-2 involved nodes, Dr. Gold said.
To tease out the natural history of stage IA- to II cancers and identify predictive factors for worse outcomes, he and colleagues combed through SEER data to identify patients with local or local-regional gastric adenocarcinoma who underwent surgery and pathologic evaluation of at least 15 lymph nodes, and who also had disease-specific survival data. They found that 2,431 patients had stages IA - IIA disease.
Not surprisingly, 887 patients with stage IA disease (T1N0) had the best odds, with a 5-year DSS of 91%. The investigators determined that these patients would be unlikely to benefit from adjuvant therapy, and excluded them from further analyses.
Among patients with stages IB through IIA disease, 5-year DSS rates ranged from 81% for patients with T1N2 and T2N0 disease, to 66% for patients with T1N1, T2N1, and T3NO disease.
In univariate analysis, factors associated with worse outcomes were older age (P less than .001), higher grade disease (P = .03), larger tumor size (P less than .001), proximal vs. distal location (P less than .001), T stage (P = .006), and TN grouping (P = .004).
In multivariate analysis, variables associated with worse outcomes were age (relative risk 1.025, P = .001), moderately or poorly differentiated or undifferentiated vs. well differentiated cancers (RR, 2.160, 3.323, and 3.306, respectively, P = .004 for all), size (RR, 1.027, P = .001) and location relative to the antrum/pylorus (gastric body RR, 1.289, and cardia/fundus RR, 2.508, P = .001 for both comparisons).
However, neither T stage, N stage nor TN grouping were independent predictors of outcome, the investigators found.
Based on these variables, they devised a risk score for stages IB-IIA, with each of the following four factors receiving 1 point: age greater than 60, tumor size greater than 5 cm, proximal location (cardia or fundus), and histologic grade other than well differentiated.
Under this risk classification system, they saw that 5-year DSS with no risk factors (two patients) was 100%, compared with 86% for patients with one risk factor (92 patients), 76% for those with two risk factors (325), 72% for those with three (372 patients), and 48% for those with all four (136 patients, P less than .001).
The study was internally funded. Dr. Gold reported having no relevant disclosures.