Lee Dippel was worried about a large mole on his back when he went to a walk-in clinic four years ago.

The doctor told him not to worry about it.

"It was just an ugly mole that I could cover up with a T-shirt, so I left it for quite some time," the 32-year-old schoolteacher told CBC News.

When the mole started to bleed later on, he finally got a second opinion.

It turned out that it was malignant and today he has stage four melanoma.

"There’s no stage five," he said.

Dippel advises people to seek a second opinion if they are concerned about a mole of their own.

Dr. Cory Goldberg, a plastic surgeon in Toronto, said that he agrees.

"When I see people who are that worried about something, I like to refer them to somebody else to get another opinion anyways just so they have, you know, that peace of mind," Goldberg said.

While not every brown spot can be referred to a specialist, Goldberg said it’s important that patients make their doctor aware of their family history.

Goldberg said early detection is key.

Dippel now goes for treatment biweekly.

He told CBC News that he is responding well to trial treatment, but wishes he had got a second opinion much sooner.

"I can’t help but wonder why he didn’t refer me to a dermatologist, but I try to just look forward and hope that things will continue as good as they have been recently," he said.

Dippel is considering suing the doctor he initially consulted. But that’s an expensive undertaking and he wants to get better first.

The Canadian Cancer Society says an estimated 6,000 people in Canada were expected to be diagnosed with melanoma last year.

Click on the video above to see a full report from the CBC's Michelle Cheung.