Reply to “Can one outcome be used to predict the other outcome?”

Sep 29, 2026

Letter to the editor replying to comments on a gastric cancer study. Defines overall survival (OS) as time from operation to death or latest follow-up, and disease-free survival (DFS) as survival after surgery without recurrence. Explains how progression-free survival (PFS) is used for noncurative surgery and stage IV disease. Discusses differences in recurrence patterns between gastric and ovarian cancer and addresses adjuvant S-1 use for stage II–III after curative surgery, noting OS–DFS discrepancy may widen with future chemotherapy and immunotherapy.

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Reply to “Can one outcome be used to predict the other outcome?”

Survival endpoints definitions (OS, DFS, PFS)

Recurrence patterns and clinical interpretation

Adjuvant S-1 and future implications

J Chin MedAssoc Letter to the editor Reply to “Can one outcome be used to predict the other outcome?” Meng-Chao Chena,b, Hsuan-Yu Suc,d, Yen-Hao Sue,f,g,h, Kuo-Hung Huangc,d,i,*, Wen-Liang Fangc,d,i, Chii-Wann Lina, Ming-Huang Chend,j, Yee Chaod,j, Su-Shun Lod,k, Anna Fen-Yau Lid,l, Chew-Wun Wuc,d aDepartment of Biomedical Engineering, National Taiwan University, Taipei, Taiwan, ROC; bDepartment of Neurosurgery, China Medical University Hospital, Taipei Branch, Taipei, Taiwan, ROC; cDivision of General Surgery, Department of Surgery, Taipei Veterans General Hospital, Taipei, Taiwan, ROC; dSchool of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan, ROC; eDepartment of Surgery, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan, ROC; fDivision of General Surgery, Department of Surgery, Shuang Ho Hospital, Taipei Medical University, New Taipei City, Taiwan, ROC; gDivision of General Surgery, Department of Surgery, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan, ROC; hTMU Research Center of Cancer Translational Medicine, Taipei Medical University, Taipei, Taiwan, ROC; iGastric Cancer Medical Center, Department of Surgery, Taipei Veterans General Hospital, Taipei, Taiwan, ROC; jCenter of Immuno-Oncology, Department of Oncology, Taipei Veterans General Hospital, Taipei City, Taiwan, ROC; kNational Yang Ming Chiao Tung University Hospital, Yilan, Taiwan, ROC; lDepartment of Pathology, Taipei Veterans General Hospital, Taipei, Taiwan, ROC DEAR EDITOR, Thank you for your comments1 for our article.2 Overall survival (OS) was defined from the date of operation to the date of death or the latest follow-up. Disease-free survival (DFS) was defined as the length of period after surgery for gastric cancer during which the patient survived without recurrence.3 We usually use OS and DFS to evaluate the outcome of gastric cancer after curative surgery. With regard to progression-free survival (PFS), it usually applies to evaluate the therapeutic results of patients who receive noncurative surgery or stage IV disease under chemotherapy, radiotherapy, or other palliative treatment. The disease etiology and the recurrent pattern between gastric cancer and ovarian cancer are quite different. Once gastric cancer recurrence after curative resection, it usually causes fetal disease course. Surgery usually gets limited benefit if gastric cancer recurrence or distant metastasis. To my knowledge, debulking surgery plays an important role if recurrence of ovarian cancer after surgery. Patients may receive second or third debulking surgery if recurrence of ovarian cancer. It may be the reason why PFS is quite important for ovarian cancer. For gastric cancer, the recurrent patterns in our series were defined as locoregional recurrence, peritoneal dissemination, distant lymph node metastasis, and distant organ (hematogenous) metastasis. Patients could have more than one metastasis at the time of initial diagnosis of recurrence. That’s why gastric cancer is fetal when recurrence. In the “Method” section, we have described hat S-1 has been used as adjuvant chemotherapy for stage II or III disease after curative surgery at our institute based on its proven survival benefit since 2008. Before 2008, there is no effective adjuvant treatment for stage II or III gastric cancer after radical gastrectomy with D2 lymph node dissection. Once gastric cancer recurrence after gastrectomy, the disease course is short and the progression is very fast. In our database, we both had OSand DFS for gastric cancer after gastric resection. The discrepancy of survival curve is relative similar between OS and DFS. However, with the development of more effective chemotherapy and immunotherapy, it may increase the difference of OS and DFS in gastric cancer after surgery in the future. REFERENCES 1. Lee FK, Lee WL. Can one outcome be used to predict the other outcome? J Chin Med Asso

FAQs

How are overall survival (OS) and disease-free survival (DFS) defined in this reply?

OS is defined from the date of operation to death or the latest follow-up. DFS is defined as the period after surgery during which the patient survives without recurrence.

When is progression-free survival (PFS) typically used?

PFS is used to evaluate therapeutic results for patients undergoing noncurative surgery or with stage IV disease receiving chemotherapy, radiotherapy, or other palliative treatments.

What role does S-1 adjuvant chemotherapy play after curative gastrectomy in the described institute?

S-1 is described as an adjuvant chemotherapy for stage II or III disease after curative surgery based on proven survival benefit since 2008, whereas before 2008 there was no effective adjuvant treatment for stage II–III after radical gastrectomy with D2 dissection.

Sep 29, 2026

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