A new cancer therapy that targets a "shield" that protects tumors from the immune system has surprised scientists by causing all trial participants to go into complete remission, representing what is claimed to be the first time such success has been found. The therapy prevented participants with advanced rectal cancer from needing chemotherapy, radiotherapy, or surgery to remove large parts of their colon, changing – and possibly saving – their lives. This study is published in the New England Journal of Medicine.

This study done on 18 patients was very small. All the patients in the study had taken the same medicine. The results of the study were shocking. The cancer had completely disappeared from the body of every patient involved in the trial. Physical examination, endoscopy, PET scan or MRI of any patient. It didn't show up in the scan. Dr Diaz said, 'I think this is the first time in the history of cancer.'

On average, one in five patients have some sort of adverse reaction to drugs like the one the patients took, dostarlimab, known as checkpoint inhibitors. The medication was given every three weeks for six months and cost about $11,000 per dose. It unmasks cancer cells, allowing the immune system to identify and destroy them.

While most adverse reactions are easily managed, as many as 3 percent to 5 percent of patients who take checkpoint inhibitors have more severe complications that, in some cases, result in muscle weakness and difficulty swallowing and chewing.