Combined S-1 chemotherapy improves the outcomes of patients with advanced colorectal cancer

This study compared two different chemotherapy treatments in metastatic colorectal cancer (mCRC; spread to other parts of the body). Researchers suggested that 24-hour infused irinotecan (Camptosar) plus oral S-1 (Teysuno) chemotherapy and bevacizumab (Avastin) is well tolerated and associated with improved outcomes.

Colorectal cancer is a very common cancer worldwide. The standard treatment for this cancer is surgery and chemotherapy. A significant number of these patients present with mCRC at diagnosis. Chemotherapy treatment in mCRC is of limited effectiveness. Therefore, new treatment regimens are always necessary.

Oxaliplatin (Eloxatin) or irinotecan chemotherapy plus bevacizumab have been used as a first-line treatment for mCRC. However, oxaliplatin-based regimens are associated with high rates of side effects which can result in treatment withdrawal. Irinotecan is usually given as a 90-minute continued injection. Some studies have shown that a 24-hour infused irinotecan resulted in improved anti-tumor activity. However, no studies have compared the effectiveness of 90-minute and 24-hour infused irinotecan.  

S-1 is a combination of drugs tegafur/gimeracil/oteracil. It is given as oral tablets. The safety and effectiveness of a 24-hour infused irinotecan, combined with S-1 and bevacizumab compared to other standard treatments for mCRC have not been investigated.

The effectiveness of 24-hour infused irinotecan and fluorouracil-based chemotherapy with bevacizumab in mCRC is not well known.

This study included information about 120 patients with mCRC who did not receive previous treatment. Of these, 61 received 24-hour irinotecan and S-1 chemotherapy with bevacizumab (group 1). The remaining 59 received FOLFIRI (folinic acid, fluorouracil, irinotecan) chemotherapy combined with bevacizumab (group 2). In group 2, irinotecan was given as a 90-minutes infusion. Treatment was repeated every 4 weeks. The average follow-up period was 22.8 months.

Progression-free survival (PFS; time from treatment to progression) and overall survival (OS; time from treatment to death by any cause) were measured.

The 1-year PFS rate was 43.14% in group 1 and 19.15% in group 2. Patients from group 1 had a 69% improvement in the odds of a better PFS. The average PFS time was 10.2 months in group 1 and 10 months in group 2.

The average OS was 29.7 months in group 1 and 28.8 months in group 2. The overall response rate was 86.3 in group 1 and 61.7% in group 2. Serious side effects such as diarrhea, loss of appetite and nausea were more commonly reported in group 1. 

This study concluded that 24-h infused irinotecan plus S-1 and bevacizumab is a good and safe option for the treatment of patients with mCRC.

This study had a small number of participants. Larger studies are needed.