WAILUKU — Willie K describes his mother as a tough former bartender who could beat up sailors and “put the fear of God in me.” But when the longtime Maui entertainer told her he had lung cancer, he said it was the first time he’d seen her cry.

“I didn’t realize the impact it would cause for her,” Willie K said Sunday. “She lost her baby son at a very young age to cancer, and she just couldn’t contain herself after I told her I had it. I just want you to know Mom, I love you no matter what.”

Willie K’s mother sat in the crowd during his post-Super Bowl performance at the Maui Arts & Cultural Center on Sunday, one of his few appearances in the coming months as he undergoes chemotherapy.

His company, Maui Tribe Productions, announced Saturday that the 57-year-old musician had been diagnosed with limited stage, small-cell carcinoma localized to his upper right lung. He started the first of four rounds of chemotherapy, which will continue over a 12-week period. In the meantime, he’s decided to limit his performances to focus on his treatment.

Karey Kapoi, a family friend speaking on behalf of Maui Tribe Productions, said Sunday that Willie K was diagnosed Jan. 19 and had just finished his first round of chemotherapy. He wasn’t ready to give an interview to the media yet.

Despite the treatment, Willie K was all smiles as he jammed and belted out tunes on stage with the K.D. Russell Band following the Super Bowl. In between songs, he talked about his cancer diagnosis with the crowd.

“I want to kill this thing like it’s the Seahawks,” he joked.

Born and raised in Lahaina as Willie Kahaialii, he developed a musical talent and love of the blues from his dad, also a highly respected musician. The second of nine boys and four girls, Willie K played in the family band and learned to play the guitar, bass, ukulele and other instruments, according to his website.

He grew to become a prolific entertainer and winner of 19 Na Hoku Hanohano awards. Known for a versatile style that can jump from Hawaiian to jazz to reggae and rock, Willie K has performed with many other big-time artists, including Prince, Mick Fleetwood, Stephen Tyler, Willie Nelson and Santana. He collaborated on several albums with fellow Maui singer Amy Hanaiali’i Gilliom. Their album “Amy and Willie Live” earned them a Grammy nomination in 2005.

Kapoi has known Willie K for more than 20 years, and said that when she heard the news, “I think my heart shattered a little bit.”

“I’ve always thought of him as being invincible just because of who he is,” Kapoi said. “He’s almost larger than life, not just on stage but to know him as a friend. . . . It was heartbreaking, but I have every confidence in his ability to beat this.”

Kapoi said the musician has rescheduled some of his performances and canceled his California tour. Any performances over the next few months will depend on how he feels. The family hopes that he’ll be able to heal and resume his regular schedule by early summer.

“Thankfully, he’s gotten some help from some friends within the industry to help cover” some shows, Kapoi said. “He’s just gotten a real outpouring of love from his peers. . . . This really demonstrates the sort of unique camaraderie within the Hawaiian music industry.”

Willie K expressed gratitude for the widespread support in the statement from Maui Tribe Productions on Saturday.

“This has been a whirlwind experience, but with the love and support of family and friends, I’m optimistic that we will beat this, and be back on stage in no time,” he said. “I also want to thank my doctor, and her team for their swift, expert action in treating me — we are lucky to have such caring health care professionals in Hawaii, and their compassion has been a key component in this process.”

Family and friends are planning to host fundraisers on his behalf statewide to make up for the lost income from shows and his health care expenses.

Art Vento, president and chief executive officer of the Maui Arts & Cultural Center, said Willie K has performed every year since the center started its Super Bowl viewing party four years ago.

“Willie has been a rock steady force and a pillar of strength in the music industry and Maui,” Vento said. “So if there’s anyone that can fight this battle with the determination and strength required, it’s Willie.”

* Colleen Uechi can be reached at cuechi@mauinews.com.