Multibeam inverse intensity-modulated radiotherapy (IMRT) for whole breast irradiation: a single center experience in China

Hybrid Treatment Planning for Chest Wall Irradiation Utilizing Three-Dimensional Conformal Radiotherapy (3DCRT), Intensity-Modulated Radiation Therapy (IMRT), and Volumetric Modulated Arc Therapy (VMAT): A Systematic Review

Novel hybrid approaches for chest wall irradiation show promising outcomes regarding target coverage and sparing organs at risk (OARs). In this systematic review, we compared hybrid volumetric modulated arc therapy (H-VMAT) or hybrid intensity-modulated radiotherapy (H-IMRT) techniques with non-hybrid techniques, such as three-dimensional conformal radiation therapy (3DCRT), field-in-field (FIF), intensity-modulated arc therapy (IMRT), and volumetric modulated arc therapy (VMAT), for breast cancer patients with mastectomy. Our focus was the plan quality and dose distribution to the OARs. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist, we performed a systematic review and quality appraisal of primary studies evaluating hybrid therapy to the chest wall and the OARs. An extensive online search of PubMed and Scopus databases was conducted using appropriate keywords. The dose to the OARs (lung, heart, and contralateral breast), planning target volume (PTV), homogeneity index (HI), and conformity index (CI) were extracted. The data were then tabulated and compared for the outcomes between modalities among the studies. Nine studies that met the search criteria were selected to evaluate the PTV coverage and dosimetric results of hybrid and non-hybrid techniques. In terms of 95% PTV coverage, among nine reviewed studies, the largest difference between the two techniques was between VMAT (47.6 Gy) and H-VMAT (48.4 Gy); for the conformity index, the largest difference was noted between 3DCRT (0.58) and H-VMAT (0.79). In both cases, differences were statistically significant (P < 0.005). Two studies showed dose homogeneity improvement within the treatment target in H-VMAT (0.15 and 0.07) compared with 3DCRT (0.41 and 0.12), with a P value of <0.001. Two studies did not report on the homogeneity index, and three others observed no statistical difference. Regarding OARs, in the comparison of H-VMAT and VMAT, the largest significant change was in the volume receiving 5 Gy (V5Gy) of the ipsilateral lung and the V10Gy of the contralateral lung. For the ipsilateral lung, V5Gy was 90.7% with VMAT versus 51.45% with H-VMAT. For the contralateral lung, V10Gy was 54.9% with VMAT versus 50.5% with H-VMAT. In six studies, the mean dose of the contralateral breast was lower in hybrid techniques than in single modalities: VMAT (4.2%, 6.0%, 1.9%, 7.1%, 4.57%) versus H-VMAT (1.4%, 3.4%, 1.8%, 3.5%, 2.34%) and IMRT (9.1%) versus H-IMRT (4.69%). Although most studies did not report on monitor units and treatment time, those that included them showed that hybrids had lower monitor units and shorter treatment times. Hybrid techniques in radiotherapy, such as combining two modalities, can indeed facilitate lower doses to OARs for patients with a high risk of toxicities. Prospective clinical studies are needed to determine the outcomes of breast cancer treated with hybrid techniques.

Acute and intermediate toxicity of 3-week radiotherapy with simultaneous integrated boost using TomoDirect: prospective series of 287 early breast cancer patients

AIMS

To report toxicity of a hypofractionated scheme of whole-breast (WB) intensity-modulated radiotherapy (IMRT) with simultaneous integrated boost (SIB) to the tumor bed (TB) using Tomotherapy^® with Direct modality.

METHODS

Patients with early breast cancer, undergoing radiotherapy (RT) in 15 daily fractions to WB (prescription dose 40.05 Gy) and SIB to the TB (48 Gy), between 2013 and 2017, was analyzed. Primary endpoint was acute and intermediate toxicity assessed at the end and within 6 months from RT, according to Radiation Therapy Oncology Group (RTOG) scale. Secondary endpoints included early chronic toxicity at 12-months follow-up, using the Late Effects Normal Tissue Task Subjective, Objective, Management, and Analytic (LENT-SOMA) scale, and cosmesis using Harvard criteria.

RESULTS

The study population was of 287 patients. Acute and intermediate toxicity was collected among 183 patients with data available at the end of RT and within 6 months, 85 (46%) experienced G2 toxicity and 84 (46%) G1 toxicity, while 14 (8%) did not report toxicity at any time. A significant reduction of any grade toxicity was observed between the two time points, with the majority of patients reporting no clinically relevant toxicity at 6 months. At univariate analysis, age < 40 years, breast volume > 1000 cm³ and D_max ≤ 115% of prescription dose were predictive factors of clinically relevant acute toxicity (G ≥ 2) at any time. At multivariable analysis, only age and breast volume were confirmed as predictive factors, with Relative Risks (95% Confidence Intervals): 2.02 (1.13-3.63) and 1.84 (1.26-2.67), respectively. At 12-month follow-up, 113 patients had complete information on any toxicity with 53% of toxicity G < 2, while cosmetic evaluation, available for 102 patients, reported a good-excellent result for 86% of patients.

CONCLUSIONS

Hypofractionated WB IMRT with a SIB to the TB, delivered with TomoDirect modality, is safe and well-tolerated. Most patients reported no toxicity after 6 months and good-excellent cosmesis. Predictive factors of clinically relevant toxicity might be considered during treatment planning in order to further reduce side effects.

Adjuvant breast inversely planned intensity-modulated radiotherapy with simultaneous integrated boost for early stage breast cancer : Results from a phase II trial

PURPOSE

To report early toxicity and 5‑year clinical outcomes of adjuvant breast inversely planned intensity-modulated radiotherapy with simultaneously integrated boost (IMRT-SIB) after breast-conserving surgery for early stage breast cancer patients.

PATIENTS AND METHODS

In all, 467 patients including 406 invasive breast cancer and 61 ductal carcinoma in situ (DCIS) were enrolled in a single institutional phase II trial. All patients underwent IMRT-SIB treatment to irradiate the whole breast and the tumor bed. Doses to whole breast and surgical bed were 45 and 60 Gy, respectively, delivered in 25 fractions over 5 weeks. The grade of maximum acute skin toxicity during treatment was recorded. Lung toxicity was noted within 6 months and patient-reported cosmetic outcomes were recorded at the 12 month follow-up after the end of radiotherapy. Clinical outcomes were assessed during follow-up.

RESULTS

Median follow-up time was 5.46 years. Median age was 46 years old (range 22-70 years old). No patient with DCIS had a local recurrence or distant metastasis. Among 406 patients with invasive breast cancer, the unadjusted 5‑year actuarial rate of locoregional control was 98.7% (95% confidence interval [CI] 97.5-100), and distant metastasis-free survival 98.7% (95% CI 97.4-100), respectively. Acute skin toxicity was recorded at grade 0-1 in 76.5% of patients, and grade 2 in 23.5% of patients. None of these patients had grade 3 or more than grade 3 skin toxicity. Grade 1 pneumonitis was found in 25.3% of patients. Assessment of patient reported cosmetic outcomes at the 12 month follow-up showed good or excellent outcome in 86.5% of cases.

CONCLUSIONS

The use of inversely planned IMRT-SIB as part of breast-conserving therapy results in optimal 5‑year tumor control and minor early toxicities.

Low rate of positive margins and re-excision after partial mastectomy in highly selected breast cancer patients: A Chinese single-institution experience

A recent randomized controlled trial firstly demonstrated that cavity shaving significantly decreased the rate of positive margins and re-excision among partial mastectomy (PM) patients. However, it remains unknown whether cavity shaving should be routinely applied to Chinese breast cancer patients undergoing PM. A total of 408 PM patients undergoing 410 PMs among 1796 surgically treated breast cancer patients at Fudan University Shanghai Cancer Centre from January 2015 to June 2015 were included in our study. Data were analysed with univariate or multivariate analysis. Overall, 11 of 410 cases (2.7%) had positive margins postoperatively. Moreover, only 24.6% of the cases (P<0.05) presented with ductal carcinoma in situ (DCIS), among whom 10.0% obtained positive margins. In multivariate logistic regression analysis, presence of mammographic calcifications was significantly associated with margin positivity (P<0.05, OR=6.06, 95% CI: 1.53-23.91). In conclusion, cavity shaving during PM should not be routinely performed in Chinese breast cancer patients, particularly in highly selected cases with a low prevalence of DCIS. PM patients with preoperative mammographic calcifications were more likely to have positive margins and might benefit more from cavity shaving.

External beam radiation techniques for breast cancer in the new millennium: New challenging perspectives

Radiation therapy in breast cancer has evolved dramatically over the past century. It has traveled a long path touching different milestones and taking unprecedented turns. At the end, a fine tune of clinical understanding, skill, technological advancement and translation of radiobiological understanding to clinical outcome has taken place. What all these have given is better survival with quality survivorship. It is thus prudent to understand breast irradiation in a new perspective suitable for the current millennium.

Predictive parameters for selection of electronic tissue compensation radiotherapy in early-stage breast cancer patients after breast-conserving surgery

Electronic tissue compensation (eComp) is an external beam planning technique allowing user to manually generate dynamic beam fluence to produce more uniform or modulated dose distribution. In this study, we compared the effectiveness between conventional three-dimensional conformal radiotherapy (3DCRT) and eComp for whole breast irradiation. 3DCRT and eComp planning techniques were used to generate treatment plans for 60 whole breast patients, respectively. The planning goal was to cover 95% of the planning target volume (PTV) with 95% of the prescription dose while minimizing doses to lung, heart, and skin. Comparing to 3DCRT plans, on the average, eComp treatment planning process was about 7 minutes longer, but resulted in lower lung V20Gy, lower mean skin dose, with similar heart dose. The benefits were more pronounced for larger breast patients. Statistical analyses were performed between critical organ doses and patient anatomic features, i.e., central lung distance (CLD), maximal heart distance (MHD), maximal heart length (MHL) and breast separation (BS) to explore any correlations and planning method selection. It was found that to keep the lung V20Gy lower than 20% and mean skin dose lower than 85% of the prescription dose, eComp was the preferred method for patients with more than 2.3 cm CLD or larger than 22.5 cm BS. The study results may be useful in providing a handy criterion in clinical practice allowing us to easily choose between different planning techniques to satisfy the planning goal with minimal increase in complexity and cost.