Susan Claveria, 72, was diagnosed with early-stage breast cancer more than a decade ago.

But instead of getting chemotherapy, which can cause harsh side effects, the Waipahu resident skipped the standard regimen and used less severe radiation and hormone pills to treat the disease.

The outcome was the same, according to a groundbreaking national study that found that early-stage breast cancer patients with the most common form of the disease do not benefit from chemotherapy.

“My feeling at that time was I did not want to go through chemo because I have seen other friends who have suffered during chemotherapy,” said Claveria, who first took a genetic test to gauge the risk of recurrence before being randomly selected for the non-chemo group. Her oncologist had originally recommended chemotherapy. “I feel like I was lucky, and I do know that because I did not go through chemo I had to maintain a healthier lifestyle in order to ward off any possible cancer recurrence. So far I’ve been cancer free.”

The University of Hawaii Cancer Center helped develop the largest breast cancer study, enrolling 172 Hawaii patients onto the TailorX clinical trial, which found that hormone therapy alone produced results as good as both chemotherapy and hormone treatment for 70 percent of women post-surgery.

The five-year survival rate was 98 percent for women who received hormone pills alone and 98.1 percent for those who received both therapies. At nine years, the rates were 93.9 percent and 93.8 percent, respectively. The findings were based on 10,273 women who participated in the study from 2006 to 2010. ECOG-ACRIN Cancer Research Group based in Philadelphia conducted the clinical trial, supported by the National Cancer Institute, a number of foundations and sales of the breast cancer research postage stamp, which provided more than $5 million.

Breast cancer is the most common cancer among Hawaii women, with about 1,107 new cases diagnosed each year. An average of 125 residents die of breast cancer locally each year; the disease is most frequently diagnosed in women ages 55 and older, according to the UH Cancer Center’s Hawaii Tumor Registry.

Most women fall into the early-stage breast cancer intermediate risk group and will no longer need to go through chemo and suffer from side effects that can include severe nausea and vomiting, anemia, hair loss and fatigue, according to researchers. As many as 70,000 patients nationwide a year could forgo the toxic drugs.

“We’re able now to spare a large group of women side effects of chemotherapy,” said Dr. Randall Holcombe, UH Cancer Center director. “We now know with this study that women in this intermediate group will have the same chance of cure by treating with a hormone pill alone. There are some side effects to hormone pills but a lot less than chemotherapy. It’s generally much milder than the side effects you get with chemotherapy. It’s significant in that it will change the standard of care.”

The hormone pill blocks estrogen, which helps promote the growth of breast tumors.

Hawaii’s participation in the study is significant because of the racial background of the population, he said. In the U.S. more than 90 percent of people who participate in cancer clinical trials are white. About 75 percent of those enrolled through the UH Cancer Center are non-white and include people of Japanese, Chinese, Korean and Native Hawaiian ancestry.

“We play a critical role in contributing information about race and ethnicity in the treatment of cancer really for everyone in the country,” Holcombe said. “It is important for people to realize that we can make a difference.”

The UH Cancer Center has between 75 and 100 clinical trials open at any given time for different types of cancer in various stages. For more information, call 586-2979.