Studies Of Intensity-modulated Radiation Therapy In Patients With Early-stage Breast Cancer After Breast-conserving Surgery

Objective To compare the homogeneity of the whole breast(clinical target volume)and irradiaion dose and volume of organs at risk between the whole breast intensity modulated radiation therapy ( IMRT) and conventional radiotherapy(CR) .To study the toxicity and curative effect of the whole breast IMRT in patients with early-stage breast cancer treated with breast-conserving surgery.Methods One hundred and three patients with early breast cancer after breast-conservative surgery were received the whole breast IMRT between Oct.2004 and Aug.2005. Prescription dose was 46 Gy for clinical target volume with 6-MV X-ray , and boost dose was 14 Gy in the tumor bed with electron. The homogeneity of the CTV and the irradiation dose and volume of lung and heart and contralateral breast were compared in the dose-volume histogram(DVH) with CR. The clinical reaction and cosmetic results effect were observed. Results For the homogeneity of CTV, the average volume proportion of 95%, 95-107% prescribed dose was 1.2%(99.1±0.81% vs 97.9±2.48% p< 0.01)and 11.8%(95.8±4.90% vs 84.0±20.7% P < 0.01) more with IMRT. the average volume proportion of 107% prescribed dose was 9.81%(4.93±8.59% vs 14.74±21.80% P < 0. 01) less with IMRT than with CR. As to normal tissue sparing in OARs, The mean dose and V20 of the ipsilateral lung were 4.1Gy(11.6±3.77Gy vs 7.50±1.97Gy P<0.01) and 7.41%(15.70±4.64% vs 23.11±7.88% P<0.01) less with IMRT .The mean dose and V5 of the contralateral breast were 2.55Gy(1.37±0.86Gy vs 3.92±4.14Gy P<0.01) and 3.57%(0.85±1.61% vs 4.42±6.56% P<0.01) less with IMRT .The mean dose and V30 of the heart for sixty-three left side breast cancer patients were 5.13Gy(3.66±2.56Gy vs 8.79±14.6Gy P<0.01) and 11.1%(4.44±3.93% vs 15.55±10.89% P<0.01) less with IMRT than with CR. Grade 1 of acute radiation skin reaction was seen in 98 patients and grade 2 in 5 patients and there was not more than grade 2 of skin reaction for all the patients . The toxicity of heart and lung was not observed during the follow-up period for all the patients. Excellent or good cosmetic outcome was 100% at 1st year and 2nd year.The local control rate were 99%,99% and 98%. The disease-free survival rate were 99%,99% and 96% at 1st year and 2nd and 3rd year.Conclusions This study suggests that the whole breast IMRT improves CTV dose distribution and improves normal tissue sparing in OARs compared with CR . the whole breast IMRT gains a satisfied result in both tumor control and cosmetic outcome in patients with early-stage breast cancer treated with breast-conserving surgery. Objective To study the dosimetric features and clinical feasibility of accelerated partial breast irradiation (APBI)carried out by intensity-modulated external-beam irradiation . Compare dose distribution and normal tissue sparing in APBI using intensity-modulated radiotherapy (IMRT) vs three-dimensional conformal radiotherapy (3D-CRT).Methods Fourteen patients with T1N0M0 breast cancer were enrolled in a Phase I prospective accelerated partial-breast IMRT protocol between January 2008 and April 2008. The clinical target volume(CTV) and the planning target volume (PTV=CTV+0.5cm) were contoured , OARs (organs at risk),including IB (ipsilateral breast), IB-PTV(ipsilateral breast excluding PTV),lung,heart and contralateral breast were contored.6 MV X-ray was selected as the radiation source and a inverse planning of IMRT was used, the prescribed dose was 34Gy/10f/5d. These cases were subsequently replanned with 3D-CRT techniques using the same contours, to compare the dose distribution patterns of IMRT vs 3D-CRT. Acute radiation skin response was recorded .Results The average planning target volume (PTV) and PTV to ipsilateral breast (IB) ratio was 159(range, 94–321cc) and 40% (range, 30–73%). The PTV volume receiving 107% of the prescribed dose was 18.7% less with IMRT than with 3D-CRT (p < 0.01).The average volume of IB-PTV receiving 25%, 50%, 75%, and 100% of the prescribed dose was 6.6%, 8.4%, 11.8%, and 10.0% less with IMRT than with 3D-CRT (p < 0.01). The irradiated heart,lung and contralateral breast volumes were small with both techniques but also favored IMRT. Grade 1 of acute radiation skin reaction(mildly hyperpigmentation) was seen in all the patients and there was not more than grade 2 of skin reaction.Conclusions For selected T1N0M0 patients, accelerated partial-breast IMRT is feasible.It improves PTV dose distribution and improves normal tissue sparing in OARs compared with 3D-CRT.However,the selection criteria for the patients,the technique protocol , dose fractionation,its influnce on late cosmetic effect ,local tumor control and survival need to be continuously follow-up in the future.