High-dose rate intraoperative brachytherapy is associated with improved outcomes in patients with high-risk rectal cancer

This study compared the effectiveness of electron beam radiotherapy (EBR) and high-dose brachytherapy (HDB) during surgery in patients with rectal cancer who underwent an incomplete removal of the cancer. Researchers suggested that HDB was associated with a lower risk of recurrence in these patients. 

Colorectal cancer is one of the most common cancers worldwide. Of these, one-third are rectal cancers. High-risk cancers can be locally advanced (starting to spread to the nearby tissues) and locally recurrent (when it comes back to nearby places). Complete removal of the tumor is the most important aim in the treatment of these tumors. If there is a risk of leaving cancer cells behind during surgery, EBR and chemotherapy are given to the patient before surgery. EBR consists of the application of radiation directly to the remaining tumor cells during tumor removal surgery. However, excessive doses are associated with negative side effects to the surrounding healthy tissues.

HDB involves placing radioactive material inside the body. This allows for higher doses of radiation to be slowly given to the tumor. As the radiation does not go to nearby organs, negative side effects are less of a risk. Prior studies suggested that applying HDB to sites where the tumor was completely removed, reduces local recurrence. However, the long-term outcomes of treatment with radiation given during surgery as EBR compared to HDB in patients with high-risk rectal cancer have not been assessed yet. 

This study included information about 215 patients with locally advanced rectal cancer (group 1). Of these, 151 (70%) received EBR while 64 (30%) received HDB. Another 158 patients with locally recurrent rectal cancer were included (group 2). Of these, 112 (71%) received EBR and 46 (29%) received HDB (group 2). Patients were followed up for up to 5 years.

In group 1, no significant difference in survival was seen between EBR and HDB. After 5 years, 47% of the HDB group were alive compared to 40% in the EBR group. The local recurrence-free survival was significantly longer in patients who received HDB. Patients who received HDB had a 50% improvement in the odds of having better survival without cancer recurrence compared to those treated with EBR.

In group 2, there were also no differences in overall survival between those treated with EBR and HDB. The average survival was 28 months for those who received HDB and 31 months for the EBR group. However, patients from group 2 treated with HDB had a 43% improvement in the odds of better survival without cancer recurrence compared to those treated with EBR.     

In group 1, complications after surgery were observed in a similar number of patients who received EBR (30%) and HDB (27%). However, in group 2 the rate of complications was higher after HDB (46%) compared to EBR (26%). 

This study concluded that HDB treatment improves survival without cancer returning in patients with locally advanced or locally recurrent rectal cancer compared to EBR.  

This study was based on data from medical records. Information might have been incomplete.