Tom Chalmers first noticed something was wrong while playing a terrible round of golf one spring day 10 years ago.

“My dad said, ‘What’s wrong with your golf game?’ ” Chalmers recalled. “I said, ‘I’m seeing two golf balls.’”

A visit to the optometrist led to a diagnosis of brain cancer. Chalmers, who was then 20 years old, had the tumor removed, underwent radiation therapy and has been in remission ever since.

But a funny thing happened on the road to recovery.

Chalmers realized that he had a hard time relating to his young peers – co-workers and friends.

“They couldn’t understand what I was going through,” said Chalmers, of Bridgton.

So several years ago he joined a young-adult cancer survivors’ group in Portland, and about two years ago helped start a similar group in Lewiston.

There typically are resources for children and older adult survivors, but “not much support for people, say, age 18-40,” Chalmers said. “I wanted to meet people who ‘got it’ and understood me.”

Chalmers said the public doesn’t expect young adults in the prime of their lives to have cancer, even though they realize it’s possible. According to the American Cancer Society, about 70,000 young adults ages 15-39 are diagnosed with cancer every year. That’s about 4 percent of the 1.6 million new cancer diagnoses a year.

Chalmers said his friends usually did not have similar experiences or know others who had undergone cancer treatment, which led to a lot of uncomfortable exchanges.

The support groups talk about how to handle work, dating, relationships and school as a young cancer survivor.

Dating is a big topic of discussion, such as when to let the person you’re dating know about the cancer diagnosis.

“When do you tell them? It’s kind of a bombshell to tell someone on a first date, but if you wait too long they say, ‘Why didn’t you tell me before?’ ” Chalmers said.

Chalmers said people dating cancer survivors want to ask about future children, but don’t know how.

“They’re too afraid to ask whether you’re able to have kids, even though they want to know,” Chalmers said. He said sometimes there’s no right or wrong answer to such questions, but it helps to talk them out.

On a recent winter day at the Cancer Community Center in South Portland, an independent nonprofit organization, Chalmers met with a group of a young cancer survivors. The session was informal, with a table full of snacks nearby. The group talked about current or past cancer treatments, their overall health and whatever else they wanted to discuss.

“I love hearing all of the stories people have. Even if you’re having a bad day, the stories are uplifting,” said Chalmers, who was treated at Dana-Farber/Boston Children’s Cancer and Blood Disorders Center.

Shannon Grant, 34, who recently relocated from South Portland to Albuquerque, N.M., said she was pregnant when diagnosed with non-Hodgkin lymphoma in 2012, so she had to deal with worries about her baby in addition to her own health.

“My baby had to go through a round of chemo while she was in the womb. I almost died, that’s how big my tumor was,” Grant said.

After Grant and her baby girl pulled through – Grant completed her treatments in early 2013 and her daughter is thriving – she sought out a support group after she had problems controlling anger.

“People kept telling me that it was great that I was alive, which was true, but I had a lot of anger and I needed a place where I could vent and feel better,” Grant said. “I was angry almost every day for a year.”

She said the support group helped her get through her anger, and in New Mexico she’s trying to start a similar group after not being able to find a young cancer survivors support group in Albuquerque.

Donna, a cancer survivor who declined to give her last name but participated in the young survivors group, said the feeling of isolation can be difficult.

“People stop inviting you to things, because they think you’re too sick to do anything,” Donna said. “I tell them, ‘Just because I’m sick doesn’t mean I’m dead.’ ”

Nationally, support for young adults with cancer has improved since the 1990s, specialists say. Support groups that have started since then include Stupid Cancer and the Young Survival Coalition for young survivors of breast cancer. Cyclist Lance Armstrong, who survived testicular cancer in his 20s, is often cited as an inspiration for young adults recovering from cancer – even though his Livestrong Foundation’s mission is to help all cancer survivors.

Breast cancer is the most common cancer found in women ages 15-39, according to the Young Survival Coalition, which was founded in 1998.

Jennifer Johnson, a coalition spokeswoman, said part of the group’s mission is to connect cancer survivors with one another, especially in rural areas where support groups may be hard to find.

“Awareness is better, but some people still don’t know that young people get breast cancer,” said Johnson, a survivor who was diagnosed with breast cancer in 1999.

Johnson, of Missouri, said she didn’t know about the Young Survival Coalition until 2002, when she attended a conference.

“I was in awe and shocked to walk into a room with 500 young women who survived breast cancer,” she said.

Chalmers said the survivors group also helps people learn how to juggle maintaining a career, starting a family and getting married while dealing with the repercussions of cancer treatment.

As for his golf game, Chalmers said he still has double vision even though he’s cancer-free. But he’s learned to adjust.

“It’s almost like I was born with double vision now,” he said. “I squint or turn my head a certain way, and hit the ball.”

Joe Lawlor can be contacted at 791-6376 or at:

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Twitter: @joelawlorph