McCain diagnosed with skin cancer

PHOENIX, Ariz. (CNN) -- Sen. John McCain has been diagnosed with malignant melanoma -- a dangerous form of skin cancer -- on his arm and temple, sources close to McCain told CNN.

The former presidential candidate and Vietnam prisoner of war will undergo further tests Thursday and Friday at a Mayo Clinic in Scottsdale, Arizona, to assess how extensively the cancer has spread. He will then consult with doctors and his family to determine a course of treatment.

Possible treatments include surgery.

Melanoma is the most lethal form of skin cancer, blamed for 7,700 deaths annually in the United States, according to the American Cancer Society. The organization also notes that 47,700 Americans will be diagnosed with the disease this year.

The area where one of the biopsies was taken is visible in this August 13 photo

When discovered early, melanoma is highly curable. But it is a very aggressive kind of cancer -- tumors can double in size every month -- and it can spread quickly to other parts of the body.

McCain was diagnosed last Thursday morning, shortly before leaving on a campaign swing with GOP presidential nominee George W. Bush.

He had traveled to the National Naval Medical Center in Bethesda, Maryland, the previous week to undergo biopsies on the two growths, a day after addressing the Republican convention in Philadelphia.

He returned to Philadelphia on Thursday with a bandage on his temple.

When asked on August 8 about the bandage, McCain said, "As part of my misspent youth I spent too much time in the sun and every few months I have to go and have some basal cell removed from my own craggy features."

Bush, who defeated McCain earlier this year in the primaries to win the Republican presidential nomination, released a statement Wednesday through his office.

"I know all Americans join Laura and me in wishing John McCain a complete and speedy recovery," Bush said. "We just came back from a visit to John and Cindy's home and our fondest thoughts are with him and his family. John is a good man and a fighter. He is in our prayers as he battles this illness."

Vice President Al Gore, getting ready to accept the Democratic nomination for president, also hailed McCain as "a great fighter" and said, "I know all Americans are praying for this to work out."

In 1993, McCain had a cancerous mole removed from his shoulder that proved to be melanoma, the most dangerous form of skin cancer, according to medical records he released in December 1999.

McCain five years ago after undergoing an extensive dermatological procedure to battle damage due to sun exposure

The records also said McCain regularly has suspicious skin lesions or moles removed -- often basal cell carcinoma, the least aggressive and most common type of skin cancer.

Dr. Michael Ambrose, a Navy physician from the Mitchell Center for Prisoner of War Studies in California -- where McCain made annual visits between 1973 and 1993 -- said in a December 1999 statement made available by the McCain campaign that the type of cancer McCain suffered in 1993 usually is due to sun exposure from years ago. Ambrose said McCain and other prisoners of war were kept in the Vietnamese sun for long periods, although it is impossible pinpoint the source of the cancer.

At the time the records were released, McCain's personal doctor, John Eckstein of the Mayo Clinic, declared McCain "cured" because there had been no signs of recurrence for more than five years.

In the past week, McCain has canceled previously scheduled campaign events with several GOP congressional candidates around the country.

McCain is on his way back from a short vacation with his wife and family on a houseboat in Lake Powell, Arizona. He will turn 64 on August 29.

The Associated Press contributed to this report.