Adding a
third dimension to the therapeutic field and reversing treatment
planning may provide safer and more effective dose delivery, according
to recent studies discussed at the Miami Breast Cancer Conference.
A
relatively new technique, intensity-modulated radiation therapy (IMRT),
builds on CT-based treatment planning, which was itself a significant
advance over early two-dimensional techniques. With the help of
sophisticated imaging, clinicians could "sculpt the radiation field and
clearly delineate normal tissue," said Lori J. Pierce, MD, professor of
radiation oncology at the University of Michigan School of Medicine in
Ann Arbor.
Use Of Costly Breast Cancer Therapy Strongly Influenced By Reimbursement Policy
What Medicare
would pay for and where a radiation oncologist practiced were two
factors that strongly influenced the choice of intensity-modulated
radiation therapy (IMRT) for treating breast cancer, according to an article published April 29 online in the Journal of the National Cancer Institute. The use of IMRT and the cost of radiation therapy increased sharply over the period of the study.
IMRT is a radiation delivery technique that modulates the radiation
beams to conform to the shape of the tumor or tumor bed in an attempt to
maximize the dose of radiation to the tumor while minimizing the dose
to adjacent normal tissues. Compared to conventional, two- or
three-dimensional radiation therapy, IMRT may reduce acute skin toxicity
and improve cosmetic outcomes for women undergoing breast conservation
therapy.
Isn't that just lovely! Not surprising! Would this new IMRT be similar to Gamma Knife? Anything to minimize the side effects as long as it does the job.
Lee xoxoxo
dx6/09,stageII,gr3,(L)mastectomy 7/09,ACx4,Taxolx7,Avastin study,gall bladder surgery 1/10,4/11 Stage 4, mets to lung, 4/11 Started Taxotere and Xeloda, 5/11 Taxotere stopped, off Xeloda
I don't think it's the same as Gamma Knife. I'm glad my insurance company is covering this procedure as it's more expensive and we all know how insurance companies can be with paying for treatment:)
Quote from the article, "Then along came IMRT, another form of three-dimensional planning that allows even more degrees of freedom," added Dr. Pierce.
Rather
than providing uniform intensities, IMRT uses computerized optimization
to break up the field and conform doses to the size, shape, and
location of the breast tumor. Intense radiation can reach targeted
cancer cells with minimal exposure to healthy tissues.
The result is a "more colorful picture," said Dr. Pierce. "But does it actually translate into benefits for patients?"
She
shared highlights from a growing body of evidence that suggests it just
might, thanks not only to improved dose delivery but also to decreased
acute and long-term toxicities."
DX IDC TNBC 6/09 age 49, Stage 1,Grade 3, 1.5cm,0/5Nodes,KI-67 48%,BRCA-,6/09bi-mx, recon, T/C X4(9/09) 11/10 Recur IM node, Gem,Carb,Iniparib 12/10,MRI NED 2/11,IMRT Radsx40,CT NED11/13,MRI NED3/15
In Patients With Early Breast Cancer, Intensity Modulated Radiotherapy Reduces Side Effects
Intensity modulated radiotherapy (IMRT) gives better results than standard radiotherapy in patients with early breast cancer, according to results from a randomised trial presented today (Sunday) to the 2nd Forum of the European Society for Radiotherapy and Oncology (ESTRO). IMRT is an advanced, high-precision form of radiotherapy that can deliver an even dose of radiation, thus reducing the cosmetic problems that can often occur after breast radiotherapy.
"We believe that this study, the largest prospective trial in the world to test breast IMRT against standard two-dimensional radiotherapy, will be practice-changing at an international level," said Dr Charlottes Coles, from Addenbrooke's Hospital Oncology Centre, Cambridge, UK. "Analysing the results five years after treatment, we saw significant benefits in patients who had received IMRT."
The researchers analysed the radiotherapy treatment plans of 1145 patients with early breast cancer who had previously had breast-conserving surgery. The plans were screened to see if they would produce an uneven radiation dose with standard two-dimensional radiotherapy (2DRT). A total of 71% of the plans fell into this category, and those patients were randomised between standard 2DRT and IMRT. The 29% of patients whose plans would not produce an uneven dose were treated with standard 2D RT, but still followed up within the trial.
One of the aims of external radiotherapy is to treat the target - in this case the whole breast - with an even dose distribution, i.e. within a range of 95% to 107% of the prescribed dose. Too low a dose can risk tumour recurrence, and too high a dose can cause undesirable side-effects such as skin changes.
"The problem with 2D breast radiotherapy is that the dose distribution is only recorded across the central part of the breast. Usually it meets the 95-107% constraints, but the shape of the breast changes, so if the same plan is looked at in 3D, then there may well be areas with overly high doses. By modulating the intensity of the radiation beam, IMRT can be used to correct for this and smooth out the dose," said Dr Coles.
The researchers set out to see whether the effect of using IMRT in those patients who would have received a dose greater than 107% to parts of their breast with 2DRT would translate into clinical benefit. IMRT planning uses results from scans to determine the dose intensity that will best treat the tumour, and therefore is more complex and time-consuming than 2DRT planning, so there was an important need to see a clear advantage to patients from the use of the procedure.
The only previous study looking at this was much smaller, and rather than picking out all patients with doses greater than 107% and randomising them, it only included women with larger breasts who are already known to be more likely to have regions of dose above the upper limit. "Our trial was more inclusive as all women were able to take part and we could quantify those who would receive an uneven dose," said Dr Coles.
"We saw that fewer patients in the IMRT group developed skin telangiectasia (dilated blood vessels near the surface of the skin), and the overall cosmetic effect in the breast was better," she said. Although there was no significant difference between the two groups in breast shrinkage, breast oedema, breast induration (hardening), and pigmentation changes, the benefits of using IMRT in these patients were clear.
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