In 2006, during his (second) battle with cancer, Matthew Larsen was stuck at home most of the time. Rather than sit around and mope, he set himself up at his beloved piano and started writing music again. The results can be heard on the debut album from Matthew Larsen and The Documents, and live at the Iron Horse this week.

In 2000 Larsen was diagnosed with Hodgkin’s Lymphoma, underwent six months of chemotherapy, and fought his way back to health. Unfortunately, doctors found a tumor in his chest in 2005, and, as it’s relatively uncommon for the insidious disease to return after 4-plus years, decided on a more intensive treatment.

He’s dubbed his release Apheresis, a procedure he endured at the Dana Farber Cancer Institute in Boston. “Basically the way it works is that they pass your blood through an apheresis machine to separate out certain parts,” he says. “In my case, they first took my own stem cells out, gave me a ton of chemo for a few weeks, then transplanted these same stem cells back in to try and help the immune system. It worked, I guess.”

Larsen says he wanted to give a nod to his cancer history since it informed so much of his songwriting. “Stem cells are awe-inspiring,” he says. “I like the idea that the thing that helps you heal is something that comes from you in the first place—something you might not have even realized existed or what function it serves. Writing music is the same way for me. What I start with develops and becomes its own thing. It gets built upon and grows. In the end it winds up being something I’d have never imagined it would be,” Larsen says. “I never knew it was inside of me.”

Recording was made possible by The Andrea Coller Memorial Award, presented to Larsen by Andrea Coller’s family and The SAMFund, an organization that assists cancer survivors with the transition to post-treatment life. Andrea Coller, a musician, lost her battle with cancer in 2008.

Larsen has worked with many of the Valley’s best musicians. For this CD, The Documents—guitarist Greg Saulmon and Larsen’s cousin Steve Biegner on drums—were joined by David Chalfant (The Nields), Mark Schwaber (Lloyd Cole and the Small Ensemble), Aric Bieganek and Rebekah Dutkiewicz (Oweihops, Northernly), Ethan Tufts (State Shirt), Matthew Loiacano (Matthew Carefully, Kamikaze Hearts), and Philip Price (Winterpills).

“I am just really lucky to have talented friends who are willing to spend some time with my music,” says Larsen. “When I look at the list of people who’ve helped with this record, I’m in absolute awe.”

Larsen says that a lot of his “indie folk piano pop” tunes emanate from humming and singing sessions in the car, transferred to his dining room piano once he gets home.

Words are a different story. “Lyrically, things take a really long time for me,” he says. “I only write a few lines at a time. Much of the time I wind up taking lyrics and sometimes melodies here and there from various unfinished songs to make one complete song. I’m an indecisive guy.”

Larsen and The Documents take the stage Sept. 11, and he promises surprise guests, special news, and a freebie regarding the new record.

Matthew Larsen and the Documents and Fiesta Brava: Sept. 11, 10 p.m., Iron Horse, Northampton, www.matthewlarsenmusic.com.