A new, small cancer study may give hope to patients with solid tumors in the stomach, esophagus or rectum.

The standard surgery includes removing portions of the body where the cancer occurred.

The study, conducted at Memorial Sloan Kettering Cancer Center, looked at a group of 103 patients, The New York Times reported.

They were given an immunotherapy drug that overrides how the body allows the immune system to block cancer treatments. No other drugs, except for the immunotherapy treatment, dostarlimab, were given. Basically, it allows the immune system to recognize cancer cells and attack them, NBC News reported.

Forty-nine patients who had rectal cancer, the tumors went away, and in the past five years, the cancer did not come back.

A majority of the other patients who had stomach, esophagus, liver, endometrium, urinary tract and prostate cancer also did not have a recurrence.

Of the 103 patients, only five had cancer return. Three of those had extra immunotherapy doses, while a fourth had cancer appear in a lymph node and had it removed. All four had no recurrence of cancer. The fifth patient’s tumor shrank after they were given extra immunotherapy, the Times reported.

Maureen Sideris was one of the patients who were treated with immunotherapy for gastroesophageal cancer. She had a tumor that blocked part of her esophagus, and would have required the removal of part of her esophagus and stomach, followed by chemotherapy and radiation, a treatment she said, “would have been horrendous.”

But she had immunotherapy treatment two years ago and is considered in remission, NBC News reported.

While they have hope that it could be a key in fighting cancer, it won’t work for everyone. They must have a cancer that has a mismatch repair deficiency, where a mutation doesn’t allow DNA to fix a problem when cells replicate, leading to more mutations.

The mismatch repair deficiency happens more frequently than in others. Only about 16% of ovarian cancer has it, while as much as 30% of endometrial cancer has the mutation, NBC News reported.

Cleveland Clinic gastrointestinal medical oncologist Dr. Suneel Kamath said very few cancers have the mutation, only “1%-2% of cancers at most,” she said, adding, “Unfortunately, this is not going to be something that is a cure-all.”

Weill Cornell Medicine surgical oncologist Dr. Heather Yeo said the treatment may be something to consider eventually.

“Immune therapies have a ton of potential. This shows we might be able to start with that,” Yeo said.

The drug, if it were used to battle cancer, may be out of reach for some, however. It costs about $11,000 a dose and nine infusions over six months need to be given. For insurance to cover it, the medical needs to be part of the clinical guidelines. It is already approved for uterine cancers with mismatch repair mutations and for the treatment of rectal cancer, but it is not yet approved for other cancers.

If someone is included in the clinical trial, the drug is given for free, the Times reported.

There are also potential side effects such as fatigue, rash, itching and in some cases lung infections and encephalitis.

The study was published in The New England Journal of Medicine and was presented at the American Association for Cancer Research meeting in Chicago on April 27.

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