Lani
11-06-2007, 07:32 AM
it is important to consider that if the tumor bed is medial (toward the midline of the body rather than towards the armpit) that there might not be (so much of or even an) advantage with regards to how much radiation the lungs and/or heart are exposed to
5 November 2007
Partial breast irradiation exposes normal tissue
MedWire News: Women who undergo partial breast irradiation (PBI) for breast cancer may receive as much exposure to the heart and lungs as those who receive standard whole breast irradiation (WBI), say US researchers.
But PBI, compared with WBI, can spare significant cardiac tissue in patients with lateralized tumor beds, the researchers note.
"We suspect there are fundamental differences in the amount of exposure to radiation a patient has using these techniques, but no one has ever looked at how much normal tissue is spared," said Laura Vallow (Mayo Clinic, Jacksonville, Florida) at the recent 2007 meeting of The American Society for Therapeutic Radiology and Oncology in Los Angeles, USA.
She added: "We are interested in the finer points of treatment planning, with the ultimate goal of making treatment more tolerable with less radiation exposure."
In the first phase of the study, the researchers enrolled 25 women with early stage breast cancer and devised computer generated radiotherapy plans for WBI and 3-D conformal PBI.
As reported at the meeting the volumes of the ipsilateral lung receiving 2.36, 4.60, 8.80, and 16.40 Gy doses were 29.7, 21.9, 12.0, and 5.8%, respectively, in PBI plans and 26.5, 17.8, 12.2, and 8.2%, respectively, in WBI plans.
"Patients are getting more exposure overall to their lungs with partial breast irradiation but less lung tissue is irradiated to higher doses compared to whole breast irradiation," Vallow summarises.
In the second phase of the study, the researchers enrolled 14 women who had undergone lumpectomy in their left breast and calculated radiation to normal heart tissue.
They found that PBI and WBI delivered about the same amount of radiation to the heart of women whose tumors were located in the middle of the breast. In women whose tumors were closer to the armpit, however, PBI spared most of the heart tissue, exposing just 2.4% at 2.5 Gy, compared with 13.5% for WBI at the same dose.
"The hope is that a short course of radiotherapy will be as effective as the much longer course, and that this could lead to increased use of breast conservation over mastectomy," Vallow said.
Vallow et al claim that by calculating these "nuances of tissue exposure" they can improve the effectiveness of PBI, which could lead to an increase in conservative treatment.
"Many women may be opting for a mastectomy instead of a lumpectomy in order to avoid weeks and weeks of radiation treatment," Vallow says.
"If the results of both methods are equivalent, then perhaps some of these women will choose less drastic surgery."
49th annual meeting of The American Society for Therapeutic Radiology and Oncology; Los Angeles, USA: 28 October - 1 November 2007
http://www.redjournal.org/
5 November 2007
Partial breast irradiation exposes normal tissue
MedWire News: Women who undergo partial breast irradiation (PBI) for breast cancer may receive as much exposure to the heart and lungs as those who receive standard whole breast irradiation (WBI), say US researchers.
But PBI, compared with WBI, can spare significant cardiac tissue in patients with lateralized tumor beds, the researchers note.
"We suspect there are fundamental differences in the amount of exposure to radiation a patient has using these techniques, but no one has ever looked at how much normal tissue is spared," said Laura Vallow (Mayo Clinic, Jacksonville, Florida) at the recent 2007 meeting of The American Society for Therapeutic Radiology and Oncology in Los Angeles, USA.
She added: "We are interested in the finer points of treatment planning, with the ultimate goal of making treatment more tolerable with less radiation exposure."
In the first phase of the study, the researchers enrolled 25 women with early stage breast cancer and devised computer generated radiotherapy plans for WBI and 3-D conformal PBI.
As reported at the meeting the volumes of the ipsilateral lung receiving 2.36, 4.60, 8.80, and 16.40 Gy doses were 29.7, 21.9, 12.0, and 5.8%, respectively, in PBI plans and 26.5, 17.8, 12.2, and 8.2%, respectively, in WBI plans.
"Patients are getting more exposure overall to their lungs with partial breast irradiation but less lung tissue is irradiated to higher doses compared to whole breast irradiation," Vallow summarises.
In the second phase of the study, the researchers enrolled 14 women who had undergone lumpectomy in their left breast and calculated radiation to normal heart tissue.
They found that PBI and WBI delivered about the same amount of radiation to the heart of women whose tumors were located in the middle of the breast. In women whose tumors were closer to the armpit, however, PBI spared most of the heart tissue, exposing just 2.4% at 2.5 Gy, compared with 13.5% for WBI at the same dose.
"The hope is that a short course of radiotherapy will be as effective as the much longer course, and that this could lead to increased use of breast conservation over mastectomy," Vallow said.
Vallow et al claim that by calculating these "nuances of tissue exposure" they can improve the effectiveness of PBI, which could lead to an increase in conservative treatment.
"Many women may be opting for a mastectomy instead of a lumpectomy in order to avoid weeks and weeks of radiation treatment," Vallow says.
"If the results of both methods are equivalent, then perhaps some of these women will choose less drastic surgery."
49th annual meeting of The American Society for Therapeutic Radiology and Oncology; Los Angeles, USA: 28 October - 1 November 2007
http://www.redjournal.org/