Dr. Robert Haruo Oishi, a Honolulu surgeon and breast cancer researcher whose work helped show that many patients could be treated effectively without a mastectomy, died Jan. 13. He was 76.

Oishi served as a principal investigator for the National Surgical Adjuvant Breast and Bowel Project. His team showed that many women with breast cancer could survive with non-invasive treatments just as well as women who had mastectomies, said Dr. Kenneth Sumida, director of medical education at Kuakini Medical Center.

Such findings "impacted the treatment of breast cancer in wo-men across the world," Su-mida said.

Oishi's research group showed that patients' chances of survival could be improved with anti-hormone treatments and chemo-therapy drugs. The researchers were also pivotal in defining which patients should receive these treatments.

"He was everyone's mentor," said Sumida, who was a medical student when he met Oishi in the late 1970s. "He set high standards for the residents."

Sumida was former chief of surgery and director of surgical education at Kuakini Medical Center.

Colleagues also credited Oishi for nurturing the state's clinical trials program that collected data on cancer and determined effectiveness of treatments.

"He was instrumental," said Dorothy Coleman, manager of the clinical trials unit at the Cancer Research Center of Hawai'i. "Last year, the University of Hawai'i received recognition as one of the top 25 accruers of patients onto these studies at NSABP (National Surgical Adjuvant Breast and Bowel Project). It's an honor because we're not very big."

Throughout a career of more than 50 years, Oishi mentored many doctors.

"He believed that it's not enough just to operate," said Dr. Mark Mugiishi, who was a resident at Kuakini Medical Center and was trained by Oishi. "You have to teach to make sure the next generation of surgeons are well trained. He did that passionately.

"He also believed in making sure that you looked at improving health outcomes for the whole community. He believed in getting patients to enroll in clinical trials to participate, and to get physicians to contribute data to nationwide data banks."

Oishi was born Nov. 28, 1933, in Kapa'a, Kaua'i. He was a 1951 graduate of 'Iolani School and earned his undergraduate and medical degrees from Tufts University in Boston. He served in the Army from 1964 to 1965, then opened a general surgical practice in Honolulu.

Oishi is survived by his wife, Elaine; daughter, Elna Ward; son, Stanton; brother, Noboru; sisters, Grace Kagawa and Akiye Oishi; and two grandchildren.

Visitation is 3 to 4 p.m. Sunday at Nu'uanu Memorial Park & Mortuary; service at 4 p.m. No flowers.