Three years on, although she's in good health, her doctors have only just managed to get her hormone levels right so that she's not constantly tired or off-colour.
However, the upside of that year of sickness means that it doesn't count on Anna's scholarship.
With that in mind, she recently returned to Oregon State to begin a post-graduate degree in public health.
Anna's racked up a series of sporting achievements while she's been at Oregon State.
Most first year rowing students spend a year or more working their way up to the top team. Not Anna.
She was in the top boat only a term after arriving, and in the stroke seat (the rower who sets the rhythm) six weeks later.
Once the worst of her illness was past, she was back to training and the top boat.
This year she was named a rowing All-American, an honorary national team composed of outstanding amateur sportspeople. Only 20 All-American rowing awards are given out annually and Anna was the first Oregon State University rower to be named in five years.
"You never really expect it, she said, "but I was pretty stoked."
A sports scholarship to an American university is no cushy number. As well as studying fulltime, the athletes train 20 hours a week. Many drop out because they can't handle the load. Anna said it paid to be well-organised, but her cancer was a huge challenge.
"I found it quite difficult because I was pretty much sick for three years. Some people can't do it at full health, but I decided what I wanted to do and I did everything I could until I got there."
Anna had surgery and radiation treatment and has been on hormone therapy since, but said it had taken a long time to get her levels in balance. She was given the all-clear in December 2012 and still has regular check-ups and scans.
Anna flew back to Oregon 10 days ago to begin her post-graduate studies and, after that, she hopes to get into graduate school with a scholarship, preferably at an Ivy League university.
Another option is to return to New Zealand because she needs to be in the country to make the Olympic rowing team.
"I'm kind of at a crossroads at the moment because rowing is an all or nothing kind of thing, so trying to decide what's more important to me - a gold medal or a career."
"It's one or the other, you can't do both so I'm undecided as to what's more important to me, education or athletic ambition. But I've got another year to figure it out."