BRUNSWICK, Maine — U.S. Sen. Angus King, I-Maine, announced Monday he would undergo surgery later this week to remove prostate cancer.

This is the second occurrence of cancer in the former Maine governor, who was diagnosed with malignant melanoma, an aggressive form of skin cancer, 40 years ago.

“Thanks to the doctors who caught it early, and my health insurance, I was cancer-free within months,” the senator, who turned 71 in March, said in a release.

King’s physicians discovered the prostate cancer during an annual physical in April.

“Let’s face it; cancer is a scary word to hear,” King wrote. “So it might seem unusual to say this, but today, I actually feel pretty fortunate. The fact is, millions of Americans bravely and quietly fight more aggressive cancers than mine every day. Many of them do so in the face of great financial hardship and without the support of their friends and family. I cannot imagine the strength it must take to carry on against that kind of adversity.

“In my case, the doctors found my cancer early,” he continued. “We have a plan to treat it, and plan for a full recovery. So when you see me on the Senate floor in a couple of weeks, or during the August work period in Maine, or on the campaign trail in a couple of years, you will see that I’m back to work with as much energy and dedication to serving you that I promised nearly three years ago. And, I will return with a renewed sense of commitment to standing up for the people of Maine.”

King experienced no symptoms or signs of the disease, according to the release, but a routine medical exam in April showed abnormalities in his blood work that indicated possible prostate cancer. A subsequent biopsy confirmed it.

A series of body scans during the past month showed no sign of spread outside the prostate area, substantially improving the prognosis for successful treatment, the release said.

Upon learning of the diagnosis, King called his brother-in-law and close friend, John Herman, a senior member of the medical staff at Massachusetts General Hospital in Boston. Herman arranged consultations with urological-oncological specialists who are now directing King’s treatment.

Dr. Douglas M. Dahl will perform the surgery on Friday at Mass General. King requested the surgery occur on the first day of the July 4 congressional recess to minimize his absence from Washington.

“I’m looking forward to a full recovery and to continuing my service in the Senate,” said King, who was elected to the Senate in 2012. “And no, this does not affect my intention to run for re-election, except my poor little prostate won’t be along for the ride.”

King said he told his family about his diagnosis in May and informed his staff Monday morning during a conference call.