Tom Marsilje, the oncology researcher whose late-stage colon cancer diagnosis turned him into an internationally known patient advocate and prolific writer, died Tuesday after a five-year fight against the disease. He was 45.

Even as his cancer progressed, Dr. Marsilje's boundless optimism and stoicism were evident. He continued to blog and contributed to publications including the Inquirer and Philly.com. Just last week, he wrote on his Facebook page to thank his many followers: "As my health deteriorates, I couldn't do it w/o you!! A temporary situation I assure you!"

Positivity defined Dr. Marsilje, said Rebecca Keller, executive director and president of the WunderGlo Foundation, an advocacy organization founded by her daughter Gloria Borges, who died of colon cancer at 32.

"My daughter's mantra was 'love life and be grateful,' " Keller said. "That's what drew Tom to our organization. Tom really loved that energy. It's kind of a never-give-up spirit. That's why his hope would never go away. You don't fear the end.  But you continue to forge ahead and do good and smile."

Dr. Marsilje's career in cancer research began at SUNY-Buffalo, where he received his doctorate in medicinal chemistry. That was followed by a post-doctoral position at Scripps Research Institute, then jobs with Millenium Pharmaceuticals and Novartis Research Foundation.

He was diagnosed on June 4, 2012 – the same day he attended a major oncology conference that showcased positive clinical trial results from a cancer drug he helped to develop.

"Just six hours later, everything changed," he wrote in his initial Inquirer column. "I awoke from a colonoscopy to hear these words: 'He has colon cancer.'…"After an initial panic, the oncology scientist in me began to take control. At that point, I began to approach my cancer as the greatest research project of my entire life."

At first, he continued juggling a full-time job, treatment and, of paramount importance, time with his wife Veronica and two young daughters, Amelie and Eleni, who sometimes appeared in his Inquirer articles. The California resident also continued running about 20 miles a week, even finishing a triathlon while undergoing chemotherapy.

Tom Marsilje after completing the running leg of his first team triathlon.
James Cuevas.
Tom Marsilje after completing the running leg of his first team triathlon.

But in 2015, as his disease progressed, he began joining online support groups and launched his blog, Adventures in Living Terminally Optimistic.

As a Newsweek magazine profile of Dr. Marsilje recounted four months ago, he started the blog as a password-protected update for family and friends, then nervously decided to go public with it.

"It became more popular than he'd ever expected—getting about 10,000 views per post from 150 countries and parts of it being translated into six languages," Newsweek said.

That led him to write a column called The Currently Incurable Scientist for the patient website Fight Colorectal Cancer. He also helped found the Colontown Clinic, made up of scientists who explain clinical trials to patients and caregivers on the online community Colontown.org.

He took pride in his writing, carefully crafting his messages for audiences ranging from patients to scientists to Inquirer and Philly.com readers. "I think the newspaper column format leads me to do my absolute best writing," he wrote of his Inquirer work. "There is a strict 500 word limit. Working under those constraints, I have to chose my words very carefully!"

In May, Dr. Marsilje launched his most innovative project, a website called Tom's MSS Trials for CRC, in collaboration with Fight CRC and the health technology company Flatiron Health. The website was an outgrowth of his personal spreadsheet listing clinical trials that might benefit him – and of his frustration with clinicaltrials.gov, the government's comprehensive list of human studies.

Dr. Marsilje's website provides patients with a curated, searchable, consumer-friendly list. The criteria in his search algorithm include whether the trial has the potential to really benefit late-stage patients.

"As a cancer researcher who was working to identify his own cure, Tom's story was in itself compelling and inspiring to others affected by cancer," said John Novack, director of communications at Inspire, an online patient community with more than one million members. "He immersed himself in the community of cancer patients and caregivers, sharing his insights. In return, he appreciated the information and comfort he received from others online. He radiated positivity, signing his notes with 'To Life!' and you could see how he buoyed the spirits of others around him, in person and online."

Tom Marsilje described his all-in approach as his “cannonball life,” even as cancer was slowly draining his strength this past summer.
Judy Alvara
Tom Marsilje described his all-in approach as his “cannonball life,” even as cancer was slowly draining his strength this past summer.

Indeed, Dr. Marsilje's Facebook post on Oct. 31 was devoid of self-pity and full of hope even as he hinted that the end might be near:

"If I have been very quiet the past week, that is where I have been. Being helped like a rag doll. A situation I never in a middle of a thousand years ever thought I would find myself in. Keep in mind, it may just happen to you too… but like me, you can find resolve in the HOPE that the situation is only temporary and that the ship will quickly right itself where it needs to be. If I am not correct, I will deal with the new situation as I have always tried to – get back on that horse with grace, humility and the feeling of  'this was just meant to be.' "