Babe Ruth is diagnosed with a Malignant Tumor in his neck

In 1946, he began experiencing severe pain over his left eye.

In November 1946, a visit to French Hospital in New York revealed Ruth had a malignant tumor in his neck that had encircled his left carotid artery. He received post-operative radiation therapy. Before leaving the hospital in February 1947, he lost approximately 80 pounds (35 kg).
Around this time, developments in chemotherapy offered some hope. A new drug named teropterin, a folic acid derivative, was developed by Dr. Brian Hutchings of the Lederle Laboratories. It had been shown to cause significant remissions in children with leukemia. Ruth was administered this new drug in June 1947. He was suffering from headaches, hoarseness and had difficulty swallowing. He agreed to use this new medicine but did not want to know any details about it. All the while he was receiving this experimental medication, he did not know it was for cancer. On June 29, 1947, he began receiving injections and he responded with dramatic improvement. He gained over 20 pounds (9 kg) and had resolution of his headaches. On September 6, 1947, his case was presented anonymously at the 4th Annual Internal cancer Research Congress in St. Louis. Teropterin ended up being a precursor for methotrexate, a now commonly used chemotherapeutic agent.

It is now known that Ruth suffered from nasopharyngeal carcinoma (NPCA), a relatively rare tumor located in the back of the nose near the eustachian tube. Contemporary management for NPCA includes concurrent chemotherapy and radiation therapy.
On April 27, 1947, the Yankees held a ceremony at Yankee Stadium. Despite his health problems, Ruth was able to attend "Babe Ruth Day". Ruth spoke to a capacity crowd of more than 60,000, including many American Legion youth baseball players. Although lacking a specific memorable comment like Gehrig's "Luckiest man" speech, Ruth spoke from the heart, of his enthusiasm for the game of baseball and in support of the youth playing the game. (Babe Ruth speaking at Yankee Stadium)
Later, Ruth started the Babe Ruth Foundation, a charity for disadvantaged children. Another Babe Ruth Day held at Yankee Stadium in September 1947 helped to raise money for this charity.
After the cancer returned, Ruth attended the 25th anniversary celebration of the opening of Yankee Stadium on June 13, 1948. He was reunited with old teammates from the 1923 Yankee team and posed for photographs. The photo of Ruth taken from behind, using a bat as a cane, standing apart from the other players, and facing "Ruthville" (right field) became one of baseball's most famous and widely circulated photographs. It won the Pulitzer Prize.

In late 1946, after spending the years during World War II performing charitable works and raising money for the country's war efforts, Babe became ill. While he had been prone to colds before and even had pneumonia in 1942, this illness was different. For much of the second half of the year, Babe had been suffering from severe pain over his left eye. In a November visit to French Hospital in Manhattan that year, doctors found the root cause of his pain -- a malignant tumor in his neck. Even worse, the tumor surrounded his left carotid artery and Babe would need surgery to save his life.

The surgery was successful to a limited degree. While the surgeons could remove most of the tumor, they could not get it all, forcing Babe to subsequently undergo radiation treatment. By the time Babe was released from the hospital in February 1947, he seemed to be doing a bit better. Although he resumed some of his favorite outdoor activities such as golf and hunting, it was also clear that Babe was still not fully recovered. He was pale. He had lost nearly 80 pounds from his prior year's average weight. His voice was raspy due to the damage done to his larynx by the surgery to remove the tumor.