Locoregional breast radiotherapy including IMN: optimizing the dose distribution using an automated non-coplanar VMAT-technique.

BACKGROUND: Volumetric Modulated Arc Therapy (VMAT) offers better conformity, homogeneity and sparing of the heart and ipsilateral lung for locoregional radiotherapy in left-sided breast cancer compared to three-dimensional conformal radiotherapy (3D-CRT). However, conventional coplanar VMAT (cVMAT) can result in higher doses to the normal tissue on the contralateral side. This study investigates a non-coplanar VMAT-technique (ncVMAT) to mitigate this issue. MATERIAL AND METHODS: CT series of 20 left sided breast cancer patients were included for planning of locoregional breast radiotherapy including internal mammary nodes (IMN). Three treatment plans; 3D-CRT, cVMAT and ncVMAT, were generated for each patient with a prescription dose of 40.05 Gy in 15 fractions. Both VMAT-techniques consisted of a single arc in the axial plane, while ncVMAT included an additional arc in the sagittal plane. All plans were optimized to cover the clinical target volume (CTV) by 38.05 Gy for the breast and 36.05 Gy for lymph nodes, with as low as possible dose to organs at risk. RESULTS: Full CTV coverage was achieved for all plans. Both cVMAT and ncVMAT delivered more conformal and homogeneous target doses than 3D-CRT. Doses to the heart and ipsilateral lung were significantly lower with ncVMAT compared to both cVMAT and 3D-CRT. ncVMAT reduced doses to both the contralateral breast and lung compared to cVMAT and achieved levels similar to 3D-CRT for the contralateral breast and moderately higher doses for the contralateral lung. Delivery of high doses (>30 Gy) to the contralateral side was completely avoided with ncVMAT, contrary to the results for cVMAT and 3D-CRT. CONCLUSION: ncVMAT reduced doses to the heart and ipsilateral lung as compared to both cVMAT and 3D-CRT. All contralateral dose metrics were reduced with the novel ncVMAT technique compared to cVMAT, and the mean contralateral breast doses were similar to 3D-CRT.

A comparison of conventional and dynamic radiotherapy planning techniques for early-stage breast cancer utilizing deep inspiration breath-hold.

BACKGROUND: For breast cancer patients, radiotherapy increases the risk of cardiac disease. Conventional three-dimensional conformal radiotherapy (3D-CRT) in deep inspiration breath-hold (DIBH) has demonstrated substantial reduction in cardiac doses as compared to treatment in free breathing. The purpose of this treatment planning study is to investigate if dynamic techniques in combination with DIBH could improve the quality of the treatment plans and further reduce the doses to the heart and other organs at risk for early-stage breast cancer patients. MATERIAL AND METHODS: CT series in DIBH of 16 patients from a previous study were used. For each patient, treatment plans were generated with the following three techniques: 3D-CRT, tangential intensity-modulated radiotherapy (tIMRT) and volumetric modulated arc therapy with partial arcs (pVMAT). The treatment planning was performed focusing on planning target volume (PTV) coverage, V95% >95%. Dose-volume histograms were calculated and compared. Doses to the heart, left anterior descending (LAD) coronary artery, ipsilateral and contralateral lung as well as the contralateral breast (CB) were assessed. RESULTS: All plans fulfilled the criterion on PTV coverage. Compared to 3D-CRT, the dynamic plans obtained better dose homogeneity and conformity. The mean heart dose was similar for 3D-CRT and tIMRT, 1.3 and 1.1 Gy, respectively, but significantly higher for pVMAT, 1.6 Gy. The median V25 Gy to the heart was 0% for all techniques. The LAD doses were generally lower with the dynamic techniques. The mean doses to the ipsi- and contralateral lung and CB were similar with tIMRT and 3D-CRT but significantly higher with pVMAT. V20 Gy to the ipsilateral lung was significantly lower with tIMRT compared to 3D-CRT. CONCLUSION: tIMRT and 3D-CRT with DIBH are better techniques for sparing heart tissue and other organs at risk without compromising target coverage in early-stage breast cancer irradiation compared to VMAT.

Pulmonary function tests - an easy selection method for respiratory-gated radiotherapy in patients with left-sided breast cancer.

PURPOSE: The purpose of this study was to establish a feasible and convenient method for selection of the subset of patients with left-sided breast cancer for whom respiratory-gated radiotherapy (RT) would be necessary to meet the national recommendation regarding radiation dose to the heart. MATERIAL AND METHODS: The volume of heart receiving a dose equal to or higher than 25 Gy (V25Gy), the mean heart dose (Dmean) and total lung volume (TLV-CT) were obtained from treatment plans based on computer tomography (CT) series recorded during free breathing (FB), and the correlation between dose to the heart and TLV-CT was studied. Second, the correlation between TLV-CT and TLV defined from three pulmonary function tests (PFTs); spirometry, gas diffusion and plethysmograhy, was evaluated. RESULTS: Dose to the heart (V25Gy and Dmean) decreased with increasing TLV-CT. Pearson's correlation coefficient (r) for TLV-CT versus V25Gy and Dmean was equal (r = -0.809, p < 0.01) for patients planned for tangential breast RT only, and r = -0.853 and -0.861 (p < 0.01) for patients planned for loco-regional RT. Regression analysis showed good correlation between TLV-CT and TLV calculated from pulmonary function tests (R(2) ≥ 0.717, p < 0.01). CONCLUSION: TLV defined by routine pulmonary function tests can be used to identify the subset of left-sided breast cancer patients who require respiratory-gated RT.

Radiation during deep inspiration allows loco-regional treatment of left breast and axillary-, supraclavicular- and internal mammary lymph nodes without compromising target coverage or dose restrictions to organs at risk.

BACKGROUND AND PURPOSE: Loco-regional radiotherapy of left-sided breast cancer represents a treatment planning challenge when the internal mammary chain (IMC) lymph nodes are included in the target volume. This treatment planning study evaluates the reduction in cardiopulmonary doses when radiation is given during deep inspiration breath-hold (DIBH). This was achieved without compromising dose coverage to the planning target volume (PTV). PATIENTS AND METHODS: Seventeen patients with early breast cancer, referred for adjuvant radiotherapy, were included. For each patient two computed tomography (CT)-scans were acquired; the first during free breathing (FB) and the second during DIBH. The scans were monitored by the Varian RPM respiratory gating system. Audio-visual guidance was used. The treatment planning of the two CT studies was performed focusing on good coverage (V95% > 98%) of the PTV. Doses to the heart, left anterior descending (LAD) coronary artery, lungs and contralateral breast were assessed. RESULTS: With equal PTV coverage, average mean heart dose was reduced from 6.2 Gy to 3.1 Gy in DIBH plans as compared to FB. Average volume receiving 25 Gy or more (V25Gy) was reduced from 6.7% to 1.2%, and the number of patients with V25Gy > 5% was reduced from 8 to 1 utilizing DIBH. The average mean dose to the LAD coronary artery was reduced from 25.0 Gy to 10.9 Gy. The average ipsilateral lung volume receiving 20 Gy or more (V20Gy) was reduced from 44.5% to 32.7% with DIBH. In 11 of the DIBH plans V20Gy was lower than 35%, in accordance with national guidelines, while none of the FB plans fulfilled this recommendation. CONCLUSION: Respiratory gated radiotherapy during DIBH is a suitable technique for loco-regional breast irradiation even when IMC lymph nodes are included in the PTV. Cardiopulmonary doses are considerably decreased for all dose levels without compromising the dose coverage to PTV.

Dose evaluation and risk estimation for secondary cancer in contralateral breast and a study of correlation between thorax shape and dose to organs at risk following tangentially breast irradiation during deep inspiration breath-hold and free breathing.

PURPOSE: To assess the impact of using breathing adapted radiotherapy on contralateral breast (CB) dose, to relate the thorax shape with the dose to the organs at risk (OARs) and to predict the risk for induced malignancies in CB using linear and non-linear models, following tangential irradiation of breast. MATERIAL AND METHODS: Sixteen patients with stage I-II breast cancer treatment planned with tangential fields using deep inspiration breath hold (DIBH) and free breathing (FB) techniques were included in this analysis. The dose results mainly based on DVH analysis were compared. Four parameters were defined to describe thoracic shape. Excess relative risk (ERR) for cancer induction in CB, employing linear and non-linear models was calculated. RESULTS: Average CB volumes exposed to a dose of 1 Gy is 1.3 times higher in DIBH plans than in FB plans. No significant difference in average V3Gy and V5Gy for DIBH and FB plans is observed. The average mean CB dose for DIBH and FB plans is 0.33 and 0.28 Gy, respectively. No correlation between thorax shape parameters and mean OARs dose is observed. The estimated average mean ERR with linear model is lower in FB plans (0.12) than for the DIBH plans (0.14). The estimated ERR with non-linear model is 0.14 for DIBH plans and 0.15 for FB plans. CONCLUSION: No significant difference in CB dose between DIBH and FB plans is observed. The four thorax shape parameters defined in this study can not be related to the dose at OARs using DIBH and FB radiation techniques. The ERR estimates for secondary CB cancer are nearly the same for FB and DIBH planning when using a linear and non-linear risk prediction models.

Cardiac and pulmonary dose reduction for tangentially irradiated breast cancer, utilizing deep inspiration breath-hold with audio-visual guidance, without compromising target coverage.

BACKGROUND AND PURPOSE: cardiac disease and pulmonary complications are documented risk factors in tangential breast irradiation. Respiratory gating radiotherapy provides a possibility to substantially reduce cardiopulmonary doses. This CT planning study quantifies the reduction of radiation doses to the heart and lung, using deep inspiration breath-hold (DIBH). PATIENTS AND METHODS: seventeen patients with early breast cancer, referred for adjuvant radiotherapy, were included. For each patient two CT scans were acquired; the first during free breathing (FB) and the second during DIBH. The scans were monitored by the Varian RPM respiratory gating system. Audio coaching and visual feedback (audio-visual guidance) were used. The treatment planning of the two CT studies was performed with conformal tangential fields, focusing on good coverage (V(95)>98%) of the planning target volume (PTV). Dose-volume histograms were calculated and compared. Doses to the heart, left anterior descending (LAD) coronary artery, ipsilateral lung and the contralateral breast were assessed. RESULTS: compared to FB, the DIBH-plans obtained lower cardiac and pulmonary doses, with equal coverage of PTV. The average mean heart dose was reduced from 3.7 to 1.7 Gy and the number of patients with >5% heart volume receiving 25 Gy or more was reduced from four to one of the 17 patients. With DIBH the heart was completely out of the beam portals for ten patients, with FB this could not be achieved for any of the 17 patients. The average mean dose to the LAD coronary artery was reduced from 18.1 to 6.4 Gy. The average ipsilateral lung volume receiving more than 20 Gy was reduced from 12.2 to 10.0%. CONCLUSION: respiratory gating with DIBH, utilizing audio-visual guidance, reduces cardiac and pulmonary doses for tangentially treated left sided breast cancer patients without compromising the target coverage.

[Recurrence and survival after breast-conserving treatment of breast cancer]. / Residiv og overlevelse etter brystbevarende behandling av brystkreft.

BACKGROUND: The objective of this retrospective study was to determine, within one institution, local relapse rate and survival for women with early-stage breast cancer treated with breast-conserving surgery followed by radiotherapy. MATERIAL AND METHODS: All women with infiltrating early-stage breast cancer who underwent post-operative whole breast irradiation at our institution in the period 14.06.99-8.03.2002 were included in the study. A CT-based 3D dose calculation was performed in all patients. RESULTS: 222 women received 50 Gy whole-breast irradiation after breast-conserving surgery in the study period. 51 patients received adjuvant systemic therapy according to national guidelines. Median age at diagnosis was 59 years (34-82 years). Median tumour size was 12 mm (1-30 mm) and 86.5 % of the patients were N0. During a follow-up (median) of 96 months (28-111 months), local recurrence was observed in three of 222 patients (1.4 %; 95 % CI [0.5-4.4 %]) in the ipsilateral breast. The estimated 8-year breast-cancer specific survival was 95 % and total survival was 90 %. INTERPRETATION: Our data demonstrate excellent local disease control in women with low-risk early-stage breast cancer (about 25 % were on adjuvant systemic therapy) who undergo breast-conserving surgery and 50 Gy whole-breast irradiation.

[Radiotherapy after breast-conserving surgery in the treatment of breast cancer: early results from a non-university hospital in Norway]. / Strålebehandling etter brystbevarende kirurgi.

BACKGROUND: In 1998 the first radiotherapy unit located outside a university hospital in Norway was established at Rogaland Central Hospital. MATERIAL AND METHODS: Results from 222 consecutive patients treated between June 1999 and March 2002 are presented. Median time to follow up was 25 months (range 8-41). All patients underwent a lumpectomy combined with a complete axillary dissection or a sentinel node biopsy. The entire breast was irradiated using 6MV photon energy to a total dose of 50 Gy. RESULTS: As of October 2002, there has not been registered any local breast failures. Three patients developed distant metastases and subsequently died from their disease. Contralateral breast cancer has occurred in one patient. The relative number of patients treated with breast conservation therapy, as compared to the total number of patients operated, has not changed after a unit of radiotherapy was established locally. INTERPRETATION: Our findings show that radiotherapy after breast-conserving surgery can be performed safely in a non-university hospital such as Rogaland Central Hospital.