CHICAGO—Targeted intraoperative radiotherapy (TIR) for breast cancer, in which radiotherapy is confined to the area of the breast where the tumor has been removed, has been found to be as good as whole breast radiotherapy at reducing breast cancer recurrence. Most important, the new data presented at the 46th annual meeting of the American Society of Clinical Oncology showed TIR can be carried out in just one hospital visit.
The researchers say TIR for breast cancer could mean much more than convenient care for patients, as well as reduced waiting lists and substantial savings for the healthcare systems. Oncologist Michael Baum, MB, ChB, FRCS, ChM, MD(hc), professor emeritus of surgery at the University College London and chairman of the TARGITA trial, said the nurses will be the key people on this major shift in the use of radiotherapy for breast cancer.
“The oncology nurse has a pretty tough job,” said Baum, who helped set up the first oncology nurse training program in England. “They have to explain to the women the benefits and the harms of treatments. I think the oncology nurse will have to get up to speed very quickly. This trial has already attracted worldwide interest.”
After breast-conserving surgery, 90% of local recurrences occur very close to the removed tumor (index quadrant) despite the presence of multicentric cancers elsewhere in the breast. Thus, restriction of radiation therapy to the site of tumor removal (tumor bed) during surgery could be adequate for selected patients. In TARGIT-A, the researchers compared TIR with the conventional policy of whole breast external beam radiotherapy (EBRT). The prospective, randomized trial included women aged 45 years and older with invasive ductal breast carcinoma undergoing breast-conserving surgery.
In this trial, 2232 women were included. The median age was 63 years and 83% of the women were less than age 70. The median tumor size was 12 mm and 17% were lymph-node positive.
After 4 years of follow-up, there were six local recurrences in the intraoperative radiotherapy group and five in the EBRT group. This translated to very similar recurrence rates in both groups. The frequency of any complications and major toxicities were similar in the two groups. For major toxicity, the rates were 3.3% in the TIR group versus 3.9% in the EBRT group.
“The side effects have been looked at very carefully,” said Baum in an interview with The Oncology Nurse. “The toxicity levels are good in both arms. However, there is significantly more grade 3 radiation toxicity in the external beam compared with the intraoperative.”
The investigators, however, found that the intraoperative approach produced a greater incidence of seroma requiring aspiration. The incidence rate was 2.1% for the TIR group compared with 0.8% in the EBRT group.
The trial used the INTRABEAM radio therapy system, a mobile radiotherapy platform with a miniature, electronic, high-dose rate (HDR), lowenergy x-ray source. The use of lowenergy x-ray radiation eliminates the need for a specialized treatment room, in contrast to other high-energy radiation sources (linear accelerators and HDR/HDR brachy therapy systems) that require specially designed rooms. This system is set up to be used in the operating room at the time of surgery. The intrabeam radiation is applied for 20 to 30 minutes, exposing the affected tissue in the tumor bed from inside the tumor cavity.
Baum said that this study was set up to demonstrate that 25 minutes in the operating room is equivalent to 6 weeks of postoperative radiotherapy. He said that these study results will now change how women with this type of breast cancer (early invasive breast cancer suitable for breast-conserving surgery) receive their therapy. Once they are aware of this option, he thinks the demand will then be great. “I think personally the women will vote with their feet,” he told The Oncology Nurse.
Besides the obvious benefits of completing all the necessary radiotherapy in a single session at the time of surgery, TIR almost completely avoids irradiation of the intrathoracic structures such as the heart, lung, and esophagus. Baum said he hoped these trial results influence a paradigm shift from conventional radiation approaches to single-dose treatment for eligible patients.