Each time radiation therapy is delivered to a tumor for treatment, that treatment is called a fraction. The type of cancer in the body will determine how many numbers of fractions the tumor will receive. Different types of cancers in the body receive different numbers of fractions. Tumors that are surgically removed and need post-operative radiation usually require fewer fractions than if the tumor was not removed. The number of fractions for all the different cancers and situations have been determined by past experience and clinical studies. These treatment courses would be considered standard fractionation where patients would receive daily radiation.
Different Fractionation Schedules
For decades, radiation oncologists have been looking at different fractionation schedules to treat cancer. For example, some cancers have been treated twice a day, which is called hyperfractionation. “Hyper” is derived from the Greek word for over or above. If patients are treated with less than the standard number of fractions, this is called hypofractionation. “Hypo” is derived from the Greek word for under.
Hypofractionated Radiation Therapy
I want to review some new information and directions regarding hypofractionation. Hypofractionated radiation therapy is obviously more convenient for patients because of the fewer overall treatments needed to treat cancer as well as being less costly. However, the burden of proof lies in its effectiveness to treat cancer. In other words, will hypofractionation be just as effective in treating cancer with no increase in complications or adverse effects to surrounding normal tissue? Prior studies have shown that breast cancers can be effectively treated with a hypofractionated course with equivalent cure rates and low side effects. The National Comprehensive Cancer Network (NCCN) had incorporated hypofractionated radiation of breast cancer into one of their preferred recommendations.
Recently, a large institutional series was published that used moderately hypofractionated radiation therapy for prostate cancer. In this study, they used 28 fractions of radiation with intensity modulated radiation therapy (IMRT) photon radiation rather than the standard 45 fractions of radiation. The study reported on the 11 year follow up outcome of over 850 men with localized prostate cancer and found good control rates and low incidence of side effects. This course of prostate cancer treatment with photon IMRT appears to be effective for all prostate groups from low risk to high risk.
Proton Therapy vs. IMRT Photon Radiation Therapy National Study
One of the frequently asked questions concerning prostate cancer and the different treatment options is: “Is proton therapy better than standard IMRT photon radiation therapy? Currently, there are no randomized clinical trial results that have answered that question.
In efforts to answer this important and common question, Ackerman Cancer Center will soon have the wonderful opportunity to enroll men with localized prostate cancer in a national study, which will compare the cure rates and side effects between IMRT photon and proton radiation therapy. It will also compare hypofractionation versus standard fractionation using proton radiation to assess the overall cure rates and side effects. This is an exciting study, which can help clarify and answer some burning questions that both doctors and patients would like to know.