If he hadn't, he might not have learned that he had cancer.
The magnetic resonance imaging test that was ordered for Peterson showed a darkened area in his femur that was diagnosed as high-grade diffuse B-cell lymphoma after a biopsy on a piece of bone the size of a quarter that was removed from his leg.
Understandably, Peterson's mind raced through all the possibilities. "Everything runs through your mind when you hear you have cancer," he said.
These days, Peterson's mind is mostly on his status as one of the top goalkeepers in the Centennial Conference, his studies, and just about everything normal college students think about.
He was put at ease when he was told the cancer was localized in the bone marrow. Peterson went through chemotherapy and radiation treatments at the Abramson Cancer Center of the University of Pennsylvania and, except for a few missed months of lacrosse, hardly skipped a beat.
He made the trip with the team to Australia in January, although he played little, and he was there when preseason practice opened Feb. 1.
"He's an example of how people should approach problems in their lives," said Haverford lacrosse coach Mike Murphy, who coached Peterson when he was a high school freshman. "He was never down about it. With his background in athletics, he took it on like he takes on everything else. He did a lot of research as to what the lymphoma was, and found out the best ways to go about it in terms of diet and everything else. I never heard him once feel sorry for himself."
Peterson, who is from Ridgefield, Conn., and was heavily recruited out of Deerfield Academy, did not go without tribulations. The chemo treatments led to hair loss and bouts of nausea, and he dropped nearly 20 pounds. Then he spent most of December commuting from Haverford to Penn for radiation while juggling classes.
"For a while, I felt like I was in a perpetual state of fogginess," he said. "But I'm back to where I was at, about 193 pounds. Really, though, I didn't feel completely back to normal until the Franklin and Marshall game. They took a pretty big piece out of my leg, and it was hurting for a while."
The Franklin and Marshall game was April 1, meaning Peterson was still feeling the effects of his ordeal through the first eight games of the season. Murphy might not have noticed, because Peterson has been stellar in goal, leading the Fords to a No. 19 ranking in the Division III South Region. Haverford, which was 9-5 overall and 5-2 in the Centennial, heading into yesterday's game at Swarthmore.
Peterson was fourth in the conference in goals-against average (8.23), fifth in save percentage (.606), and second in saves per game (12.4) heading into the regular-season finale. He has set the school record for victories in a season, with nine. Murphy said Peterson had a good chance to be all-conference and maybe even all-American by the time his career is finished.
"He's big, strong, and has quick hands, and he's very competitive. All the things you find in a good athlete," Murphy said.
Peterson said the cancer had altered his personality: Problems that used to seem so important and frazzled him are now much easier to handle.
"A lot of times, I used to get too worked up about some things," he said. "But now I just take a deep breath and let the chips fall where they may, and do what I know I can do. I guess it's because, you know, I've been very lucky. I'm free of cancer."
Contact staff writer Ray Parrillo