We conducted a retrospective review of patients who went straight to surgery for their presumed early-stage gastric cancer, or cancer which has not spread outside of the stomach (AJCC 8th edition; cT1-2, N0, M0), in the National Cancer Database diagnosed between 2004-2016. We classified patients into 3 groups: accurately staged if pathologic staging confirmed early-stage cancer, inaccurately staged with receipt of adjuvant therapy, and inaccurately staged with no receipt of adjuvant therapy.
We found approximately 40% of patients (1675/4244 ) were understaged, having more disease than expected, and we found that many patients had disease in the lymph nodes or even metastatic disease. Increased likelihood of inaccurate clinical staging was associated with clinical stage T2 tumors (which have invaded the stomach muscle layer), non-well differentiated tumors, and diffuse-type histology.
The implications of this inaccurate clinical staging are significant. The standard of care for patients who have regional disease that has spread to the lymph nodes is a combination of chemotherapy and surgery to reduce the risk of cancer recurrence. Treatment begins with the chemotherapy, which is important because it treats any micrometastatic disease that may be present. People who have chemotherapy before surgery tolerate the chemotherapy better. For patients who go to surgery first and have lymph node disease, as many of the patients in our study did, that opportunity to control micrometastatic disease is missed.
Factors Associated with Understaging
Of patients who were inaccurately staged, only 54% received adjuvant therapy, which is guideline-concordant care, and may be associated with overall survival. The 5-year overall survival was significantly higher in patients with accurate staging than in either of the inaccurately staged groups (70% accurately staged, 45% inaccurately staged with receipt of adjuvant therapy, and 40% inaccurately staged with no receipt of adjuvant therapy; p<.0001).