S1 FOR ADJUVANT TREATMENT OF PANCREATIC CANCER 

Adjuvant chemotherapy with the oral agent known as S-1 (Taiho Pharmaceutical) significantly increased overall survival in pancreatic cancer patients compared with gemcitabine, which is the current post-surgery treatment standard, according to a Japanese study.

The results are practice changing, said lead author Katsuhiko Uesaka, MD, PhD, medical deputy director at Shizuoka Cancer Center, Shizuoka, Japan.

"S-1 may be considered as the new standard treatment for resected pancreatic cancer patients," he said at a presscast today, held by the American Society of Clinical Oncology (ASCO) in advance of the 2013 Gastrointestinal Cancers Symposium, January 24 through 26, in San Francisco.

However, the implications of the study, which only involved Japanese patients, may be limited to Asian populations.

Dr. Uesaka said other studies have shown that, in white people, diarrhea related to S-1 treatment was problematic. Additional studies are needed, in which adjustments in dose and schedule might rectify this adverse event, he added.

In the current study, the investigators randomized 385 patients with stages I-III pancreatic cancer to postoperative treatment with S-1 or gemcitabine.

The 2-year survival rates were 70% and 53% for S-1 and gemcitabine, respectively, in an interim analysis (scheduled after 180 deaths; P < .0001 for superiority). This translated to 44% lower risk for death for the S1 patients compared with the gemcitabine patients.

Relapse rates were also better in the S-1 arm. The 2-year relapse-free survival rates were 49% and 29% for S-1 and gemcitabine, respectively.

The investigators will continue to follow the study participants for at least 5 years.

An expert agreed that S-1 can potentially change current practice. "For the first time, we now have another option…and it appears superior," said Neal J. Meropol, MD, who moderated the presscast. He is from the Case Western Reserve University School of Medicine in Cleveland, Ohio.

Dr. Meropol pointed out that, although most pancreatic cancer is detected at an advanced, inoperable stage, an estimated one-third of patients worldwide are eligible for surgery and adjuvant chemotherapy. "We've viewed gemcitabine as the standard therapy," he commented about adjuvant treatment.

S-1 will need to be further tested in other populations, Dr. Meropol added.

Another expert agreed. A clinical trial to determine the "appropriate use" in this setting is needed in the United States, said Kenneth Yu, MD, of Memorial Sloan-Kettering Cancer Center in New York City, who attended the press conference and provided independent commentary.

Nevertheless, Dr. Yu called the new results from Japan "very impressive" and "incredibly promising."