Intensity-modulated breast therapy approach reduces radiation-induced dermatitis

April 29, 2008

Preventing adverse skin reactions during breast radiotherapy is a challenge. Attempts to address the problem with topical creams or hygiene have been unsuccessful. Instead, Canadian researchers have gone back to the source of the problem and found that using intensity-modulated radiation therapy can reduce acute dermatitis, especially when compared with traditional whole-breast radiotherapy.

Preventing adverse skin reactions during breast radiotherapy is a challenge. Attempts to address the problem with topical creams or hygiene have been unsuccessful. Instead, Canadian researchers have gone back to the source of the problem and found that using intensity-modulated radiation therapy can reduce acute dermatitis, especially when compared with traditional whole-breast radiotherapy.

Dr. Jean-Philippe Pignol and colleagues conducted a multicenter phase III double-blinded clinical trial comparing IMRT with standard radiation therapy with wedge compensation in 331 women with early-stage breast cancer. Researchers came from the Sunnybrook Health Sciences Centre in Toronto, Vancouver Island Cancer Centre in Victoria, Durham Regional Cancer Centre in Osahwa, and Hôpital Notre-Dame in Montreal. They published their findings in the Journal of Clinical Oncology.

Of the 331 patients, 170 were randomized to receive IMRT, while 161 underwent standard treatment. In both cases, the dose was 50 Gy in 25 fractions (2 Gy per fraction). A boost dose of 16 Gy was given when appropriate.

"The two treatment arms differed by the missing tissue compensation method (2D versus 3D) used to account for variations in breast shape," the authors wrote. "The standard arm used a tungsten wedge inserted in the beam path, and the experimental arm used breast IMRT."

Clinical outcomes included intensity of acute skin reaction, pain based on the National Cancer Institute Common Toxicity Criteria (NCI-CTC), and occurrence of moist desquamation. Symptoms were recorded during therapy at weeks five to seven and then again at various intervals post-treatment, up to six weeks.

The results found that the use of breast IMRT significantly reduced the occurrence of moist desquamation, with an absolute reduction of 16.6%. There was a trend toward fewer NCI-CTC grade 3 to 4 acute skin reactions in the IMRT arm, with an absolute reduction of 9.5%.

In addition to the use of breast IMRT, smaller breast size was associated with a decreased risk of moist desquamation. The authors noted that neither a volume of breast receiving more than 10% of the prescribed dose nor the delivery of a boost dose led to an increased risk of moist desquamation. Finally, moist desquamation was associated with a higher NCI-CTC pain score.

In an accompanying editorial, Dr. Bruce Haffty and colleagues wrote that Pignol's group had demonstrated the benefits of 3D planning, including more homogeneous dose distribution to the central breast as well as the superior and inferior aspects, a reduction in hot spots, and improvements in cosmetic outcomes.

The clinical implications of the Canadian trial are manifold, they said. This IMRT-based technique could lead to decreased skin changes and fibrosis. Future studies may show that chemoradiotherapy allows for better local control in select patients, and the improved homogeneity achieved with IMRT could jumpstart other novel accelerated fractionation schemes.

Financial hurdles to the widespread acceptance of breast IMRT still remain, however, according to Haffty's group from the Cancer Institute of New Jersey in Brunswick, MD Anderson Cancer Center in Houston, and Memorial Sloan-Kettering Cancer Center in New York City.

The current technical charges for IMRT planning and delivery are significantly higher than for conventional treatment, though the reimbursement rate for IMRT in many instances in the U.S. is at the same level as standard radiotherapy, they wrote.

"Should IMRT be the standard of care for delivery of radiation to the whole breast after lumpectomy?," the commentators wrote. "It is clear from the phase III trials by Pignol et al ... that there are both dosimetric and clinical advantages to improved homogeneity ... [M]ost facilities that have the necessary planning equipment and technology ... should strive for optimal homogeneity, which can be readily achieved with the techniques described."

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