Target volume definition and target conformal irradiation technique for breast cancer patients

Systematic risk analysis of radiation pneumonitis in breast cancer: role of cotreatment with chemo-, endocrine, and targeted therapy

PURPOSE

A major complication of sequential and concomitant chemoradiation in breast cancer treatment is interstitial pneumonitis induced by radiation therapy (RT), systemic therapy, or a combination of both. Dose and volume of co-irradiated lung tissue directly correlate with the risk of radiation pneumonitis. Especially in case of combined treatment, it is often unclear which of the used therapeutic agents promote pneumonitis.

METHODS

This was a prospective monocentric study including 396 breast cancer patients. A systematic analysis of single and combined therapeutic measures was performed in order to identify treatment-related factors enhancing the risk of pneumonitis post RT.

RESULTS

Overall incidence of pneumonitis of any grade was 38%; 28% were asymptomatic (grade 1) and 10% were symptomatic (> grade 1). Pneumonitis > grade 2 did not occur. Beside age, smoking status, and mean lung dose, the combined treatment with goserelin and tamoxifen significantly enhanced the risk of pneumonitis in a supra-additive pattern (odds ratio [OR] 4.38), whereas each agent alone or combined with other drugs only nonsignificantly contributed to a higher pneumonitis incidence post RT (OR 1.52 and OR 1.16, respectively). None of the other systemic treatments, including taxanes, increased radiation pneumonitis risk in sequential chemoradiation.

CONCLUSION

Common treatment schedules in sequential chemoradiation following breast-conserving surgery only moderately increase lung toxicity, mainly as an asymptomatic complication, or to a minor extent, as transient pneumonitis ≤ grade 2. However, combined treatment with tamoxifen and the LHRH analog goserelin significantly increased the risk of pneumonitis in breast cancer patients after chemoradiation. Thus, closer surveillance of involved patients is advisable.

Call for a Multidisciplinary Effort to Map the Lymphatic System with Advanced Medical Imaging Techniques: A Review of the Literature and Suggestions for Future Anatomical Research

This review intends to rekindle efforts to map the lymphatic system by using a more modern approach, based on medical imaging. The structure, function, and pathologies associated with the lymphatic system are first discussed to highlight the need for more accurately mapping the lymphatic system. Next, the need for an interdisciplinary approach, with a central role for the anatomist, to come up with better maps of the lymphatic system is emphasized. The current approaches on lymphatic system research involving medical imaging will be discussed and suggestions will be made for an all-encompassing effort to thoroughly map the entire lymphatic system. A first-hand account of our integration as anatomists in the radiotherapy department is given as an example of interdisciplinary collaboration. From this account, it will become clear that the interdisciplinary collaboration of anatomists in the clinical disciplines involved in lymphatic system research/treatment still holds great promise in terms of improving clinical regimens that are currently being employed. As such, we hope that our fellow anatomists will join us in an interdisciplinary effort to map the lymphatic system, because this could, in a relatively short timeframe, provide improved treatment options for patients with cancer or lymphatic pathologies all over the world. Anat Rec, 302:1681-1695, 2019. © 2019 American Association for Anatomy.

Contouring consensus guidelines in breast cancer radiotherapy: Comparison and systematic review of patterns of failure

Adequate coverage of sites harbouring potential microscopic disease is paramount, where the clinical decision has been made to include regional lymph node radiotherapy for patients with breast cancer. This must be achieved in balance with minimising dose to normal tissues. Several international consensus guidelines detailing clinical target volumes (CTVs) are available, but there is currently no agreement as to which is most appropriate for a given clinical situation. Contouring guidelines are beneficial for routine practice and essential for clinical trial quality assurance. The aims of this study were as follows: to provide a single point of comparison of four commonly used contouring guidelines, including one used in a current Trans-Tasman Radiation Oncology Group trial; and to undertake a systematic review of existing studies which map sites of breast cancer recurrence against contouring guidelines. Two international consensus guidelines (European Society for Radiotherapy and Oncology, and Radiation Therapy Oncology Group) were compared with two clinical trial guidelines (TROG 12.02 PET LABRADOR and the Proton/Photon trial NCT02603341 RADCOMP). Comprehensive literature search for patterns of failure studies was undertaken using Embase and Pubmed. We detail the small but significant differences between the breast consensus guidelines, particularly the supraclavicular (SCF) and internal mammary chain CTVs. Seven series were found mapping recurrence patterns. These results are discussed in the context of the contouring guidelines. Several studies found the SCF CTV is the area at greatest risk of geographical 'miss'. This review will facilitate further discussion about guideline selection and modification, particularly for future clinical trials in Australia and New Zealand.

Inversely Planned Intensity Modulated Radiotherapy of the Breast Including the Internal Mammary Chain: A Plan Comparison Study

The aim of this paper is to evaluate the benefit of inversely planned intensity modulated radiotherapy (IMRT) in the adjuvant irradiation of breast cancer when internal mammary lymph nodes are included in the treatment volume. 20 patients treated with 3D-planned conventional radiotherapy (CRT) following breast conserving surgery were included in the study. We chose 10 patients with left-sided and 10 patients with right-sided tumors. All treatment volumes included the internal mammary chain. For plan comparison to the applied CRT plan an inverse IMRT-plan in ‘step-and-shoot’-technique was calculated.

For all patients IMRT resulted in an improved conformity of dose distribution to the target volume compared to CRT (mean COIN95: 0.798 vs. 0.514 with COIN95 = C1* C2 (C1= fraction of CTV that is covered by > 95% of the prescribed dose and C2 = volume of CTV that is covered by > 95% of the prescribed dose/total volume that is covered by > 95% of the prescribed dose). In all cases with matching adjacent beams, the homogeneity in the target volume was improved. The volume of the ipsilateral lung irradiated with a dose higher than 20 Gy was reduced with IMRT from 24.6% to 13.1% compared to CRT. For left-sided target volume the heart volume with a dose higher than 30 Gy was reduced from 6.2% to 0.2%.

The presented plan comparison study for irradiation of the breast and the parasternal lymph nodes showed a substantial improvement of the dose distribution by inversely planned IMRT compared to CRT. This is visible for the target volume, the ipsilateral lung and, in case of left-sided target volume, the heart. Despite an increase in integral dose to the entire normal tissue, the application of IMRT might be clinically advantageous in cases where no satisfying dose distribution can be obtained by CRT.

Outcome of pN0 Triple-Negative Breast Cancer with or without Lymph Node Irradiation: A Single Institution Experience

The optimal management of patients with pathologically node-negative triple-negative breast cancer (pN0 TNBC) remains unclear. We hypothesized that lymph node irradiation (LNI; internal mammary chain/periclavicular irradiation) had an impact on outcomes of pN0 TNBC. A cohort of 126 consecutive patients with pN0 TNBC treated between 2007 and 2010 at a single institute were included. All radiotherapy (breast/chest wall, ±LNI) was delivered adjuvantly, following completion of surgery ± chemotherapy. Tumors were reviewed and histologic features were described. Tissue microarrays were constructed and tumors were assessed by immunohistochemistry using antibodies against ER, PR, HER2, Ki-67, cytokeratins 5/6, 14, epidermal growth factor receptor and androgen receptor. Patients were divided into two groups for statistical analysis: LNI (LNI+) or no LNI (LNI-). We focused on disease-free survival (DFS), metastasis-free survival (MFS), and overall survival (OS). Fifty-seven and 69 patients received or not LNI, respectively. Median age was 52 (range [25-76]) and 55 (range [29-79]) in LNI+ and LNI- group (p = 0.23). LNI was associated with larger tumors (p = 0.033), central/internal tumors (33 versus 4, p < 0.01) and more chemotherapy (86% versus 59.4% p < 0.01). The median follow-up was 53.5 months. The rate of first regional relapse (associated or not with distant relapse) was low in both groups. There was no difference in 4-year DFS (82.2% versus 89.9%; p = 0.266), MFS (87.0% versus 91.1%; p = 0.286) and OS (85.8% versus 89.9%; p = 0.322) between LNI+ and LNI- group, respectively. In univariate analysis, only clinical size (T >10 mm versus ≤10 mm), histologic size (pT >10 mm versus ≤10 mm) and grade 3 (versus grade 2) were found to be significantly associated with shorter DFS. Omission of LNI in patients with pN0 TNBC does not seem to result in poorer outcome. Further studies are needed to specifically evaluate LNI in pN0 TNBC with histologic grade 3 and/or (p)T >10 mm.

[Prophylactic axillary radiotherapy for breast cancer]

Adjuvant radiotherapy, after breast conserving surgery or mastectomy for breast cancer, improves overall survival while decreasing the risk of recurrence. However, prophylactic postoperative radiotherapy of locoregional lymph nodes for breast cancer, particularly of the axillary region, is still controversial since the benefits and the risks due to axillary irradiation have not been well defined. To begin with, when performing conformal radiotherapy, volume definition is crucial for the analysis of the risk-benefit balance of any radiation treatment. Definition and contouring of the axillary lymph node region is discussed in this work, as per the recommendations of the European Society for Radiotherapy and Oncology (ESTRO). Axillary recurrences are rare, and the recent trend leads toward less aggressive surgery with regard to the axilla. In this literature review we present the data that lead us to avoid adjuvant axillary radiotherapy in pN0, pN0i+ and pN1mi patients even without axillary clearance and to perform it in some other situations. Finally, we propose an update about the potential toxicity of adjuvant axillary irradiation, which is essential for therapeutic decision-making based on current evidence, and to guide us in the evolution of our techniques and indications of axillary radiotherapy.

ESTRO consensus guideline on target volume delineation for elective radiation therapy of early stage breast cancer

BACKGROUND AND PURPOSE

Delineation of clinical target volumes (CTVs) is a weak link in radiation therapy (RT), and large inter-observer variation is seen in breast cancer patients. Several guidelines have been proposed, but most result in larger CTVs than based on conventional simulator-based RT. The aim was to develop a delineation guideline obtained by consensus between a broad European group of radiation oncologists.

MATERIAL AND METHODS

During ESTRO teaching courses on breast cancer, teachers sought consensus on delineation of CTV through dialogue based on cases. One teacher delineated CTV on CT scans of 2 patients, followed by discussion and adaptation of the delineation. The consensus established between teachers was sent to other teams working in the same field, both locally and on a national level, for their input. This was followed by developing a broad consensus based on discussions.

RESULTS

Borders of the CTV encompassing a 5mm margin around the large veins, running through the regional lymph node levels were agreed, and for the breast/thoracic wall other vessels were pointed out to guide delineation, with comments on margins for patients with advanced breast cancer.

CONCLUSION

The ESTRO consensus on CTV for elective RT of breast cancer, endorsed by a broad base of the radiation oncology community, is presented to improve consistency.

DEGRO practical guidelines: radiotherapy of breast cancer III--radiotherapy of the lymphatic pathways

AIM

The purpose of this work is to update the practical guidelines for adjuvant radiotherapy of the regional lymphatics of breast cancer published in 2008 by the breast cancer expert panel of the German Society of Radiation Oncology (DEGRO).

METHODS

A comprehensive survey of the literature concerning regional nodal irradiation (RNI) was performed using the following search terms: "breast cancer", "radiotherapy", "regional node irradiation". Recent randomized trials were analyzed for outcome as well as for differences in target definition. Field arrangements in the different studies were reproduced and superimposed on CT slices with individually contoured node areas. Moreover, data from recently published meta-analyses and guidelines of international breast cancer societies, yielding new aspects compared to 2008, provided the basis for defining recommendations according to the criteria of evidence-based medicine. In addition to the more general statements of the German interdisciplinary S3 guidelines updated in 2012, this paper addresses indications, targeting, and techniques of radiotherapy of the lymphatic pathways after surgery for breast cancer.

RESULTS

International guidelines reveal substantial differences regarding indications for RNI. Patients with 1-3 positive nodes seem to profit from RNI compared to whole breast (WBI) or chest wall irradiation alone, both with regard to locoregional control and disease-free survival. Irradiation of the regional lymphatics including axillary, supraclavicular, and internal mammary nodes provided a small but significant survival benefit in recent randomized trials and one meta-analysis. Lymph node irradiation yields comparable tumor control in comparison to axillary lymph node dissection (ALND), while reducing the rate of lymph edema. Data concerning the impact of 1-2 macroscopically affected sentinel node (SN) or microscopic metastases on prognosis are conflicting.

CONCLUSION

Recent data suggest that the current restrictive use of RNI should be scrutinized because the risk-benefit relationship appears to shift towards an improvement of outcome.

Delineation of target volumes and organs at risk in adjuvant radiotherapy of early breast cancer: national guidelines and contouring atlas by the Danish Breast Cancer Cooperative Group

During the past decade planning of adjuvant radiotherapy (RT) of early breast cancer has changed from two-dimensional (2D) to 3D conformal techniques. In the planning computerised tomography (CT) scan both the targets for RT and the organs at risk (OARs) are visualised, enabling an increased focus on target dose coverage and homogeneity with only minimal dose to the OARs. To ensure uniform RT in the national prospective trials of the Danish Breast Cancer Cooperative Group (DBCG), a national consensus for the delineation of clinical target volumes (CTVs) and OARs was required.

MATERIAL AND METHODS

A CT scan of a breast cancer patient after surgical breast conservation and axillary lymph node (LN) dissection was used for delineation. During multiple dummy-runs seven experienced radiation oncologists contoured all CTVs and OARs of interest in adjuvant breast RT. Two meetings were held in the DBCG Radiotherapy Committee to discuss the contouring and to approve a final consensus. The Dice similarity coefficient (DSC) was used to evaluate the delineation agreement before and after the consensus.

RESULTS

The consensus delineations of CTVs and OARs are available online and a table is presented with a contouring description of the individual volumes. The consensus provides recommendations for target delineation in a standard patient both in case of breast conservation or mastectomy. Before the consensus, the average value of the DSC was modest for most volumes, but high for the breast CTV and the heart. After the consensus, the DSC increased for all volumes.

CONCLUSION

The DBCG has provided the first national guidelines and a contouring atlas of CTVs and OARs definition for RT of early breast cancer. The DSC is a useful tool in quantifying the effect of the introduction of guidelines indicating improved inter-delineator agreement. This consensus will be used by the DBCG in our prospective trials.

Current clinical coverage of Radiation Therapy Oncology Group-defined target volumes for postmastectomy radiation therapy

PURPOSE

The Radiation Therapy Oncology Group (RTOG) has published consensus guidelines for contouring relevant anatomy for postmastectomy radiation therapy (RT). How these contours relate to current treatment practices is unknown. We analyzed the dose-volume histograms (DVHs) for these contours using current clinical practice at University of Texas MD Anderson Cancer Center and compared them with the proposed treatment plans to treat RTOG-defined targets to full dose.

METHODS AND MATERIALS

We retrospectively analyzed treatment plans for 20 consecutive women treated with postmastectomy RT for which the treatment targets were the chest wall (CW), level III axilla (Ax3), supraclavicular (SCV), and internal mammary (IM) nodes. The RTOG consensus definitions were used to contour the following anatomic structures: CW; level I, II, and III axillary nodes (Ax1, Ax2, Ax3); SCV; IM; and heart (H). DVHs for these contours and the ipsilateral lung were generated from clinically designed treatment that had actually been delivered to each patient. For comparison regarding dose to normal tissue, new treatment plans were generated with the goal of covering 95% of the anatomic contours to 45 Gy.

RESULTS

The prescribed dose was 50 Gy in each case. The mean percent of volumes that received 45 Gy (V45) for the RTOG guideline-based contours were CW 74%, Ax1 84%, Ax2 88%, Ax3 96%, SCV 84%, and IM 80%. Mean heart V10 values were 11% for treatment of left-sided tumors and 6% for right-sided tumors. Mean ipsilateral lung V20 values were 28% for left-sided tumors and 34% for right-sided tumors. For the contour-based plans, mean V45 values were CW 94%, Ax1 95%, Ax2 97%, Ax3 98%, SCV 98%, and IM 85%. Mean heart V10 values were 14% for treatment of left-sided tumors and 12% for right-sided tumors. Mean ipsilateral lung V20 values were 32% for left-sided tumors and 45% for right-sided tumors.

CONCLUSIONS

Clinically derived treatment plans, which have proven efficacy and are the current standard, cover 74% to 96% of the anatomy-based RTOG consensus volumes to the prescription dose. This discrepancy should be considered if treatment planning protocol guidelines are designed to incorporate these new definitions.

Quality indicators for breast cancer: revisiting historical evidence in the context of technology changes

Radiation therapy for breast cancer has considerably changed over the years, from simple simulator-based 2-dimensional techniques to sophisticated image-guided individualized treatments, with maximally protected normal structures. This has led to a substantial improvement in the outcome of breast cancer patients in terms of disease control, survival, and quality of life. This progress is based on clinical research and paralleled by progress in delivering sophisticated radiation treatment. Clinical trials resulted in identifying patients groups who will benefit from radiation treatment. They also stimulated the development of quality assurance tools and guidelines, which are now applied in daily clinical practice. The new technical opportunities to optimize dose distributions in patients require dedicated quality assurance measures because they may be more sensitive to variations throughout the treatment. Still, a large source of variation and uncertainty in radiation therapy remains in the definition of target volumes, which is clinically significant in terms of dosimetric target coverage as well as exposure of healthy tissues. This striving for continuous improvement of patient selection and treatment will lead to further improvement of local control while at the same time improving functional and cosmetic outcome and avoiding severe late complications, including cardiac toxicity.

Role of systemic therapy in the development of lung sequelae after conformal radiotherapy in breast cancer patients

PURPOSE

To analyze the risk of radiogenic lung damage in breast cancer patients after conformal radiotherapy and different forms of systemic treatment.

METHODS AND MATERIALS

In 328 patients receiving sequential taxane-based chemotherapy, concomitant hormone therapy (tamoxifen or aromatase inhibitors), or no adjuvant systemic therapy, symptomatic and asymptomatic lung sequelae were prospectively evaluated via the detection of visible CT abnormalities, 3 months or 1 year after the completion of the radiotherapy.

RESULTS

Significant positive associations were detected between the development of both pneumonitis and fibrosis of Grade 1 and patient age, ipsilateral mean lung dose, volume of the ipsilateral lung receiving 20 Gy, and irradiation of the regional lymph nodes. In multivariate analysis, age and mean lung dose proved to be independent predictors of early (odds ratio [OR] = 1.035, 95% confidence interval [CI] 1.011-1.061 and OR = 1.113, 95% CI 1.049-1.181, respectively) and late (OR = 1.074, 95% CI 1.042-1.107 and OR = 1.207, 95% CI 1.124-1.295, respectively) radiogenic lung damage, whereas the role of systemic therapy was significant in the development of Grade 1 lung fibrosis (p = 0.01). Among the various forms of systemic therapy, tamoxifen increased the risk of late lung sequelae (OR = 2.442, 95% CI 1.120-5.326, p = 0.025). No interaction was demonstrated between the administration of systemic therapy and the other above-mentioned parameters as regards the risk of radiogenic lung damage.

CONCLUSIONS

Our analyses demonstrate the independent role of concomitant tamoxifen therapy in the development of radiogenic lung fibrosis but do not suggest such an effect for the other modes of systemic treatment.

Automating RTOG-defined target volumes for postmastectomy radiation therapy

PURPOSE

Consistency in defining and contouring target structures in radiation therapy (RT) is critical for highly conformal RT, for evaluating treatment plans, and for quality assurance in multi-institutional RT trials. The Radiation Therapy Oncology Group (RTOG) has published consensus guidelines for contouring targets for postmastectomy RT. To aid in contouring such structures, we evaluated the potential use of an automated contouring technique, known as deformable image registration-based breast segmentation (DEF-SEG).

METHODS AND MATERIALS

The RTOG definitions were used to contour the chest wall (CW); levels I, II, and III axillary nodes (Ax1, Ax2, Ax3); supraclavicular (SCV) nodes; internal mammary (IM) nodes; and the heart. Left-sided and right-sided templates were created. The DEF-SEG was then used to generate auto-segmented contours from the appropriate template to computed tomographic scans of 20 test cases (10 left, 10 right). To assess the accuracy of this method, those contours were manually modified as necessary to match the RTOG definitions, and the extent of the overlap was compared. The dosimetric impact of the difference in contours was then evaluated by comparing dose-volume histograms for modified and unmodified contours.

RESULTS

Mean volume-overlap ratios between the unmodified DEF-SEG-generated contours and modified contours were as follows: CW, 0.91; Ax1, 0.68; Ax2, 0.64; Ax3, 0.68; SCV node, 0.66; IM node, 0.32, and the heart, 0.93. Mean differences in volume receiving 45 Gy (V45) for the modified versus unmodified contours were as follows: CW, 2.1%; SCV node, 4.8%; Ax1, 5.1%; Ax2, 5.6%; Ax3, 3.0%; and IM node, 10.1%. Mean differences in V10 between the modified heart and the unmodified heart were 0.4% for right-sided treatment and 0.5% for left-sided treatment.

CONCLUSIONS

The DEF-SEG can be helpful for delineating structures according to the RTOG consensus guidelines, particularly for the CW and the heart. No clinically significant dosimetric differences were found between the modified and unmodified contours. The DEF-SEG may be useful for evaluating treatment plans for postmastectomy RT in multi-institutional trials.

Simplified rules for everyday delineation of lymph node areas for breast cancer radiotherapy

The aim of this study was to present the simplified rules of delineation of lymph node (LN) volumes in breast irradiation. Practical rules of delineation of LN areas were developed in the Department of Radiation Oncology of the Institut Curie. These practical guidelines of delineation were based on different specific publications in the field of breast and LN anatomy. The principal characteristic of these rules is their clearly established relationship with anatomical structure, which is easy to find on CT slices. The simplified rules of delineation have been published in pocket format as the illustrated atlas "Help of delineation for breast cancer treatment". In this small pocket guide, delineation using the practical rules is illustrated, with examples from anatomical CT slices. It is shown that there is an improvement in delineation after the use of these simplified rules and the guide. In conclusion, this small guide is useful for improving everyday practice and decreasing the differences in target delineation for breast irradiation between institutions and observers.

Early experience of tomotherapy-based intensity-modulated radiotherapy for breast cancer treatment

AIMS

New technology - specifically intensity-modulated radiotherapy (IMRT) - is now being applied to breast radiotherapy and a recent dosimetric analysis confirmed the advantages of IMRT over 'wedge-only' plans. Such application to everyday practice raises new issues and here we present the early experience of IMRT-based breast irradiation in a single centre.

MATERIALS AND METHODS

We present cases of breast cancer treated by Tomotherapy-based IMRT, where the perceived advantages of IMRT are considerable. Cases presented are bilateral disease, left breast irradiation, pectus excavatum, prominent contralateral prosthesis and internal mammary chain disease. We discuss the practicalities of such treatment and the advantages over standard breast irradiation techniques.

RESULTS

Advantages include better conformity of treatment with lowering of dosages to underlying organs at risk, for example ipsilateral lung and heart. There is improved coverage of the planning target volume, including regional nodes, without field junction problems. Planning, quality assurance and treatment delivery are more time consuming than for standard breast irradiation and the low dose 'bath' is increased.

CONCLUSIONS

The standard radiotherapy tangential technique for breast/chest wall treatments has not significantly changed over many decades, whereas across many other tumour sites there have been great advances in radiotherapy technology. The dosimetric advantages of IMRT are readily apparent from our early experience. The wider spread of the lower dose zone (the low dose 'bath' of radiation) is a potential concern regarding late oncogenesis and methods to minimise such risks should be considered.

Technique for axillary radiotherapy using computer-assisted planning for high-risk skin cancer

High-risk skin cancer arising on the upper limb or trunk can cause axillary nodal metastases. Previous studies have shown that axillary radiotherapy improves regional control. There is little published work on technique. Technique standardization is important in quality assurance and comparison of results especially for trials. Our technique, planned with CT assistance, is presented. To assess efficacy, an audit of patients treated in our institution over a 15-month period was conducted. Of 24 patients treated, 13 were treated with radical intent, 11 with this technique. With a follow up of over 2 years, the technique had more than a 90% (10/11) regional control in this radical group. Both of the radical patients who were not treated according to the technique had regional failure. One case of late toxicity was found, of asymptomatic lymphoedema in a radically treated patient. This technique for axillary radiotherapy for regional control of skin cancer is acceptable in terms of disease control and toxicity as validated by audit at 2 years.

The risk of early and late lung sequelae after conformal radiotherapy in breast cancer patients

PURPOSE

To study the risks of early and late radiogenic lung damage in breast cancer patients after conformal radiotherapy.

METHODS AND MATERIALS

Radiogenic lung sequelae were assessed prospectively in 119 patients by means of clinical signs, radiologic abnormalities, and the mean density change (MDC) of the irradiated lung on CT.

RESULTS

Significant positive associations were detected between the development of lung abnormalities 3 months or 1 year after the radiotherapy and the age of the patient, the ipsilateral mean lung dose (MLD), the radiation dose to 25% of the ipsilateral lung (D(25%)) and the volume of the ipsilateral lung receiving 20 Gy (V(20 Gy)). The irradiation of the axillary and supraclavicular lymph nodes favored the development of pneumonitis but not that of fibrosis. No relation was found between the preradiotherapy plasma TGF-beta level and the presence of radiogenic lung damage. At both time points, MDC was strongly related to age. Significant positive associations were demonstrated between the risks of pneumonitis or fibrosis and the age of the patient, MLD, D(25%), and V(20 Gy). A synergistic effect of MLD, D(25%), and V(20 Gy) with age in patients older than 59 years is suggested.

CONCLUSION

Our analyses indicate that the risks of early and late radiogenic lung sequelae are strongly related to the age of the patient, the volume of the irradiated lung, and the dose to it.

Loco-regional conformal radiotherapy of the breast: delineation of the regional lymph node clinical target volumes in treatment position

BACKGROUND AND PURPOSE

As the location of the regional lymph nodes (LNs) of the breast varies largely between patients and may be dependant on the position of the arm, adequate localization of these nodes is mandatory in order to fully take advantage of optimized conformal radiotherapy. For this purpose, the anatomical boundaries of the regional lymph node (LN) clinical target volumes (CTVs) for delineation on transverse CT-slices, made in treatment position, were established.

PATIENTS AND METHODS

Anatomical and surgical descriptions of the regional LNs of the breast, as well as a shoulder dissection, were studied. Axial slices of a human cadaver with one arm in abduction and the other in adduction were investigated, to assess the displacement of LNs by abduction of the arm into treatment position. Based on these findings, we defined the anatomical boundaries of the regional LN CTVs visible on transverse CT-slices.

RESULTS

Standard anatomical and surgical descriptions appeared to be inadequate for determination of the boundaries of the regional LN CTVs in treatment position. With abduction of the arm, a change in position of all regional LNs, except for the medial supraclavicular LNs and internal mammary LNs, was observed in the anatomical cross-sections. This was also taken into account in our delineation protocol proposal.

CONCLUSIONS

Anatomically based guidelines for delineation of the regional LN CTVs for loco-regional irradiation of the breast on transverse CT-slices, made in treatment position, have been developed in this study. These could be used as a basis for conformal radiotherapy.

Optimizing breast cancer treatment efficacy with intensity-modulated radiotherapy

PURPOSE

To present our clinical experience using intensity-modulated radiation therapy (IMRT) to improve dose uniformity and treatment efficacy in patients with early-stage breast cancer treated with breast-conserving therapy.

METHODS AND MATERIALS

A total of 281 patients with Stage 0, I, and II breast cancer treated with breast-conserving therapy received whole breast RT after lumpectomy using our static, multileaf collimator (sMLC) IMRT technique. The technical and practical aspects of implementing this technique on a large scale in the clinic were analyzed. The clinical outcome of patients treated with this technique was also reviewed.

RESULTS

The median time required for three-dimensional alignment of the tangential fields and dosimetric IMRT planning was 40 and 45 min, respectively. The median number of sMLC segments required per patient to meet the predefined dose-volume constraints was 6 (range 3-12). The median percentage of the treatment given with open fields (no sMLC segments) was 83% (range 38-96%), and the median treatment time was <10 min. The median volume of breast receiving 105% of the prescribed dose was 11% (range 0-67.6%). The median breast volume receiving 110% of the prescribed dose was 0% (range 0-39%), and the median breast volume receiving 115% of the prescribed dose was also 0%. A total of 157 patients (56%) experienced Radiation Therapy Oncology Group Grade 0 or I acute skin toxicity; 102 patients (43%) developed Grade II acute skin toxicity and only 3 (1%) experienced Grade III toxicity. The cosmetic results at 12 months (95 patients analyzable) were rated as excellent/good in 94 patients (99%). No skin telengiectasias, significant fibrosis, or persistent breast pain was noted.

CONCLUSION

The use of intensity modulation with our sMLC technique for tangential whole breast RT is an efficient method for achieving a uniform and standardized dose throughout the whole breast. Strict dose-volume constraints can be readily achieved resulting in both uniform coverage of breast tissue and a potential reduction in acute and chronic toxicities. Because the median number of sMLC segments required per patient is only 6, the treatment time is equivalent to conventional wedged-tangent treatment techniques. As a result, widespread implementation of this technology can be achieved with minimal imposition on clinic resources and time constraints.