Breast cancer patients treated with intensity modulated radiation therapy (IMRT) instead of standard whole breast irradiation (WBI) have a lower incidence of acute or chronic toxicities, according to a study in Practical Radiation Oncology.
Chirag Shah, MD, from the department of radiation oncology at Beaumont Cancer Institute in Royal Oak, Mich., and colleagues sought to compare standard WBI to WBI with IMRT (using both a typical treatment time and an accelerated treatment time) in terms of toxicity levels for patients.
The researchers noted that 20 percent of women fail to undergo adjuvant radiation therapy as part of breast-conserving therapy. Barriers may include the five- to six-week length of WBI and concerns about potential toxicity. Previous studies had indicated that IMRT is associated with decreased toxicities—dermatitis, edema, pain, induration, and hyperpigmentation—compared with WBI, but data on accelerated WBI with IMRT were limited.
The retrospective review included 335 patients with stage 0-IIB breast cancer. A total of 87 patients underwent WBI (S-WBI), 93 underwent IMRT (I-WBI), and 155 underwent accelerated WBI with IMRT (I-AWBI). Patients in the first two subgroups were treated between 1999 and 2001; women in the latter group were treated between 2006 and 2010.
“Overall, I-WBI patients demonstrated a reduced incidence of grade 2+ acute radiation dermatitis and induration compared with I-AWBI and S-WBI,” wrote Shah and colleagues.
Patients undergoing I-WBI had lower rates of chronic edema compared with S-WBI patients and trends for improved rates of excellent cosmesis were seen in I-WBI and I-AWBI patients.
A side analysis determined that larger-breasted (more than 1600 cc) women had higher toxicity levels than smaller-breasted women, including increased levels of acute dermatitis, chronic hyperpigmentation and edema. Larger-breasted women undergoing I-WBI had significant reductions in acute dermatitis compared with similar women undergoing S-WBI and I-AWBI. The researchers also observed a trend toward decreased chronic breast edema and chronic induration in larger-breasted women who underwent I-WBI.
The findings support earlier data that showed improved toxicity profiles with the use of IMRT compared with traditional planning techniques for standard WBI, according to Shah and colleagues.
“Our data support the increasing role of IMRT in delivering not only whole breast irradiation but also whole breast irradiation using an accelerated treatment time,” Frank Vicini, MD, a radiation oncologist with Michigan Healthcare Professionals/21st Century Oncology in Farmington Hills, Mich., said in statement.
The data also support the currently accruing Radiation Therapy Oncology Group 1005 trial, concluded Shah et al.