UF radiation oncologist targets tumors with precision

As medical director of the University of Florida Proton Therapy Institute in Jacksonville, Nancy Mendenhall, M.D., not only helps heal cancer patients, but also researches innovative cancer treatments.

A UF College of Medicine faculty member since 1985, Mendenhall served as the chair of the department of radiation oncology for 13 years. Now the associate chair of the department of radiation oncology at UF Health Jacksonville, she helped inspire the development of the UF Proton Therapy Institute, which is affiliated with the UF Health Cancer Center. Currently, Mendenhall is responsible for the day-to-day clinical operations of the institute.

More than 5,000 patients have been treated at the institute since it opened in 2006. Of those, 97 percent have been involved in some kind of clinical study investigating the effects of proton therapy treatment.

Proton therapy employs targeted doses of radiation to treat cancer. Using focused beams of accelerated protons is of particular benefit when a tumor is located in sensitive areas like the lung, brain, head and neck, eye, liver, prostate or pancreas. Most of the energy from proton therapy is deposited in the tumor target, resulting in less damage to healthy tissues surrounding the tumor than conventional radiation therapy. This means that patients may have fewer negative side effects because of treatment.

“We’ll be more successful at treating cancers because we won’t have to worry as much about normal tissues,” Mendenhall said.

In addition to working with pediatric and Hodgkin’s disease patients, Mendenhall and her colleagues have conducted numerous clinical trials involving a variety of cancer types. A follow-up study with the institute’s first group of prostate cancer patients showed that 76 percent of the high-risk participants remained disease-free after five years. The number was 99 percent for participants who had low or intermediate risk.

Mendenhall and her colleagues have also studied the use of protons to treat left breast cancer as it relates to heart damage. Breast cancer patients treated with certain conventional radiation techniques may experience heart disease later in life, Mendenhall said. Comparative studies done on proton radiation and X-rays showed that proton therapy exposes patients to much less radiation.

“The impact of protons is quite significant for breast cancer, because there will be both less toxicity and better coverage of the cancer target,” Mendenhall said.