The reverse hockey stick technique: postmastectomy radiation therapy for breast cancer patients with locally advanced tumor presentation or extensive loco-regional recurrence

Dosimetric Analyses of the Three Radiation Techniques Used in the EORTC 22922/10925 IM-MS Breast Cancer Trial

PURPOSE

The aim of the current study is to compare the dosimetry of 3 radiation therapy (RT) techniques used in the EORTC 22922/10925 trial for irradiating the internal mammary (IM) and medial supraclavicular nodes (MS) using a treatment planning system available nowadays for dose calculation.

METHODS

We performed a retrospective dosimetry analysis of anonymised data; thus, ethics approval was not required. Ten cases of left-sided breast were randomly selected for RT planning to a total dose of 50 Gy in 25 fractions. The treatment planning was done according to the trial's protocol and under the supervision of the EORTC trial's coordinators. Doses to planning target volumes (PTV) and to organs at risk (OARs) are reported. Data is presented in descriptive statistics.

RESULTS

A total of 10 cases and 40 treatment plans (4 plans per case: standard-plan A, modified standard-plan B, individualised-plan C and breast-only-plan D). For all planning techniques, the mean dose to the PTV of the left breast (plan A-D) and the PTV-MS (plan A-C) exceeded 95% of the prescribed dose (>47.5 Gy). The individualised technique (plan C) had a lower coverage for PTV-IM, with a mean of 87% of the prescribed dose compared to ∼102% for plans A and B. The dose to OARs varied between techniques, with the mean heart dose being higher in the standard and modified standard techniques (18.3 and 16.6 Gy, respectively) compared to the individualised technique (9.5 Gy).

CONCLUSIONS

The 3 RT techniques used in the trial varied in target coverage and OARs dose. Our results may help to understand the observed larger absolute benefit of individualised IM-MS treatment planning in terms of breast cancer outcomes.

Clinical application of 3D-printed-step-bolus in post-total-mastectomy electron conformal therapy

The 3D-printed boluses were used during the radiation therapy of the chest wall in six patients with breast cancer after modified radical mastectomy (MRM). We measured the in-vivo skin doses while both conventional and 3D-printed boluses were placed on the chest wall and compared the mean doses delivered to the ipsilateral lung and the heart. The homogeneity and conformity of the dose distribution in the chest wall for both types of boluses were also evaluated. The uniformity index on the chest skin was improved when the 3D-printed boluses were used, with the overall average skin dose being closer to the prescribed one in the former case (-0.47% versus -4.43%). On comparing the dose-volume histogram (DVH), it was found that the 3D-printed boluses resulted in a reduction in the mean dose to the ipsilateral lung by up to 20%. The precision of dose delivery was improved by 3% with the 3D-printed boluses; in contrast, the conventional step bolus resulted in a precision level of 5%. In conclusion, the use of the 3D-printed boluses resulted in better dose homogeneity and conformity to the chest wall as well as the sparing of the normal organs, especially the lung. This suggested that their routine use on the chest wall as a therapeutic approach during post-mastectomy radiation therapy offers numerous advantages over conventional step boluses.

Contemporary Breast Radiotherapy and Cardiac Toxicity

Long-term cardiac effects are an important component of survivorship after breast radiotherapy. The pathophysiology of cardiotoxicity, history of breast radiotherapy, current methods of cardiac avoidance, modern outcomes, context of historical outcomes, quantifying cardiac effects, and future directions are reviewed in this article. Radiation-induced oxidative stress induces proinflammatory cytokines and is a process that potentiates late effects of fibrosis and intimal proliferation in endothelial vasculature. Breast radiation therapy has changed substantially in recent decades. Several modern technologies exist to improve cardiac avoidance such as deep inspiration breath hold, gating, accelerated partial breast irradiation, and use of modern 3-dimensional planning. Modern outcomes may vary notably from historical long-term cardiac outcomes given the differences in cardiac dose with modern techniques. Methods of quantifying radiation-related cardiotoxicity that correlate with future cardiac risks are needed with current data exploring techniques such as measuring computed tomography coronary artery calcium score, single-photon emission computed tomography imaging, and biomarkers. Placing historical data, dosimetric correlations, and relative cardiac risk in context are key when weighing the benefits of radiotherapy in breast cancer control and survival. Estimating present day cardiac risk in the modern treatment era includes challenges in length of follow-up and the use of confounding cardiotoxic agents such as evolving systemic chemotherapy and targeted therapies. Future directions in both multidisciplinary management and advancing technology in radiation oncology may provide further improvements in patient risk reduction and breast cancer survivorship.

Nonrandomized Comparison between Concomitant and Sequential Chemoradiotherapy with Anthracyclines in Breast Cancer

Purpose

To evaluate the tolerance of concomitant administration of anthracycline-based chemotherapy (CHT) and 3-dimensional conformal radiotherapy (RT) after breast-conserving surgery.

Methods and Materials

Sixty-seven patients, treated with conservative surgery followed by 3-dimensional whole breast RT and concomitant CHT regimens including “Canadian modified” CEF (5-fluorouracil, epirubicin, cyclophosphamide) or AC (doxorubicin, cyclophosphamide) were evaluated for toxicity. They were compared in terms in compliance and acute toxicity with 67 patients irradiated sequentially after having received anthracyclines.

Results

Acute grade ≥2 skin toxicity was significantly higher in the concomitant group compared to the sequential group, although the incidence of Grade 3 desquamation showed no statistical difference (9% vs. 3%, p = 0.14). Haematological toxicity represented the main cause of treatment discontinuation, reporting higher rate of grade 3-4 leuco-neutropenia in the concomitant group (20.9% vs. 6%, p = 0.01). Mean RT duration was longer in the concomitant group (51 days vs. 45 days) owing to RT breaks. Late toxicity was acceptable. No symptomatic lung and heart events were reported. Radiological lung hyperdensity was detected in 27.7% of the patients in the concomitant group. Post-treatment left ventricular ejection fraction significantly decreased compared with baseline, but cardiac function remained within the normal range, without any difference between left or right-sided RT.

Conclusions

Although there was more acute grade ≥2 skin toxicity in the concomitant group, the rate of grade 3 dermatitis was lower than expected, suggesting some advantages of 3-D CRT over older techniques. Haematological toxicity exerted a significant impact on both RT and CHT delivery.

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.

Delaying Radiotherapy for the Delivery of Adjuvant Chemotherapy in the Combined Modality Treatment of Early Breast Cancer: Is It Disadvantageous and Could Combined Treatment be the Answer?

Women with early stage breast cancer are increasingly being treated with both adjuvant chemotherapy and radiotherapy. The optimal sequence of these two treatment modalities is yet to be defined. It remains controversial whether delaying radiotherapy in order to deliver chemotherapy compromises local disease control and survival. Consequently, clinical practice in the UK is divided, with a number of different combination schedules being used in an effort to bring forward the start of radiotherapy. In practice, however, any benefit in local control must be balanced against a potential increase in toxicity. A review of the current literature on the effect of radiotherapy delay is presented, together with data on the toxicity of combined chemo-radiotherapy schedules and recent data from clinical trials designed to determine the optimal sequencing of chemotherapy and radiotherapy.

An improved internal mammary irradiation technique in radiation treatment of locally advanced breast cancers

The purpose of the present study was to compare a new internal mammary irradiation technique with traditional techniques for locally advanced breast cancers in terms of sparing ipsilateral lung and heart and reducing the “cold” and “hot spots” in breast tissue. The new technique uses wide tangential fields for the first eight fractions of treatment. A medial internal mammary field (IMF) of electrons matched with narrowed tangential fields is used for the remaining fractions. Intensity‐modulated radiation therapy (IMRT) by means of segmented multileaf collimation (SMLC) is used in the narrowed tangential fields to improve the match between the electron and the photon fields. Treatment planning was performed to compare this technique to a wide‐tangential‐only technique and to a traditional oblique IMF technique for three patients with differing habitus. Film dosimetry was performed in a solid water phantom to confirm the planning results. For all three patients, the mean doses of the ipsilateral lung and the heart were significantly reduced with the new technique. The lung and the heart volumes were remarkably reduced at low‐dose levels (≤12GY) compared to the traditional IMF technique, and significantly reduced at all dose levels compared to the wide tangential technique. The new technique also reduced the “cold” and “hot spots” along the match plane between the IMF and the tangential fields compared to the traditional IMF technique. In conclusion, the new IMF technique shows dosimetric improvement compared to the traditional IMF technique in terms of the critical organ sparing and target dose uniformity.

PACS number: 87.53.Tf

Lymphedema Secondary to Postmastectomy Radiation: Incidence and Risk Factors

BACKGROUND

Postmastectomy radiotherapy (PMRT) has proven benefits for certain patients with breast cancer; however, one of its complications is lymphedema. This study examines the incidence of and risk factors associated with lymphedema secondary to PMRT.

METHODS

The charts of patients treated with mastectomy at Roswell Park Cancer Institute between January 1, 1995, and April 20, 2001, who received PMRT were reviewed. Univariate analysis of patient, disease, and treatment variables was conducted. Multivariate analysis was performed on variables found to be significant in univariate analysis.

RESULTS

One hundred five patients received PMRT. The incidence of lymphedema was 27%. Patient age, body mass index, disease stage, positive lymph nodes, nodes resected, postoperative infection, duration of drainage, chemotherapy, and hormonal therapy were not associated with lymphedema. Total dose (P =.032), posterior axillary boost (P =.047), overlap technique (P =.037), radiotherapy before 1999 (P =.028), and radiotherapy at Roswell Park Cancer Institute (P =.028) were significantly associated with lymphedema. Increased lymphedema was noted with supraclavicular, internal mammary, mastectomy scar boost, and chest wall tangential photon beam radiation, but the associations were not statistically significant.

CONCLUSIONS

The high incidence and debilitating effects of lymphedema must be weighed against the benefits of PMRT. Efforts to prevent lymphedema should be emphasized.

A linear diode array (JFD-5) for match line in vivo dosimetry in photon and electron beams; evaluation for a chest wall irradiation technique

BACKGROUND AND PURPOSE

In vivo dosimetry using thermoluminiscence detectors (TLD) is routinely performed in our institution to determine dose inhomogeneities in the match line region during chest wall irradiation. However, TLDs have some drawbacks: online in vivo dosimetry cannot be performed; generally, doses delivered by the contributing fields are not measured separately; measurement analysis is time consuming. To overcome these problems, the Joined Field Detector (JFD-5), a detector for match line in vivo dosimetry based on diodes, has been developed. This detector and its characteristics are presented.

MATERIALS AND METHODS

The JFD-5 is a linear array of 5 p-type diodes. The middle three diodes, used to measure the dose in the match line region, are positioned at 5-mm intervals. The outer two diodes, positioned at 3-cm distance from the central diode, are used to measure the dose in the two contributing fields. For three JFD-5 detectors, calibration factors for different energies, and sensitivity correction factors for non-standard field sizes, patient skin temperature, and oblique incidence have been determined. The accuracy of penumbra and match line dose measurements has been determined in phantom studies and in vivo.

RESULTS

Calibration factors differ significantly between diodes and between photon and electron beams. However, conversion factors between energies can be applied. The correction factor for temperature is 0.35%/ degrees C, and for oblique incidence 2% at maximum. The penumbra measured with the JFD-5 agrees well with film and linear diode array measurements. JFD-5 in vivo match line dosimetry reproducibility was 2.0% (1 SD) while the agreement with TLD was 0.999+/-0.023 (1 SD).

CONCLUSION

The JFD-5 can be used for accurate, reproducible, and fast on-line match line in vivo dosimetry.

Chest wall irradiation with MLC-shaped photon and electron fields

PURPOSE

To improve the treatment technique for chest wall irradiation, using the multileaf collimator (MLC) of the MM50 Racetrack Microtron to shape both photon and electron beams, and to check the dose delivery in the match-line region of these fields for the routine and improved technique.

METHODS AND MATERIALS

Using diode and film phantom measurements, the optimal number of photon beam segments and their positions relative to the electron beam were determined. On phantoms, and during actual patient treatment using in vivo dosimetry, the dose homogeneity in the match-line region was determined for both the routine and improved techniques.

RESULTS

Three photon beam segments (9-mm gap, perfect match, and 9-mm overlap) were used to match the electron beam, resulting in minimum-maximum dose values in the match-line region of 88-109%, compared to 80-115% for the routine technique (2 photon beam segments). During patient treatment, the average minimum and maximum dose values were 95% and 115%, respectively, compared to 78% and 127%, respectively, for the routine technique. The interfraction variation in dose delivery was reduced from 11.0% (1 SD) to 4.6% (1 SD). The actual treatment time was reduced from 10 to 4.5 min.

CONCLUSION

Using the MLC of the MM50 to shape both photon and electron beams, an improved treatment technique for chest wall irradiation was developed, which is less labor intensive, faster, and yields a more homogeneous, and better reproducible dose delivery.

A new penumbra generator for electron fields matching

Abutment of two or more electron fields to irradiate extended areas may lead to significant dose inhomogeneities in the junction region. This paper describes the geometric and dosimetric characteristics of a device developed to modify the penumbra of an electron beam and thereby improve the dose uniformity in the overlap region when fields are abutted. The device is a Lipowitz metal block placed on top of the electron applicator's insertion plate and positioned to stop part of the electron beam on the side of field abutment. The air-scattered electrons beyond the block increase the penumbra width from about 1.4 to 2.7-3.4 cm with an SSD of 100 cm. The modified penumbra is broad and almost linear at all depths for the 9 and 12 MeV electron beams used in this study. Film dosimetry was used to obtain beam profiles and isodose distributions of single modified beams and matched fields of 9 and 12 MeV as well as matched fields of both energies. Computer simulation was used to optimize the skin gap to be used and to quantify the dose uniformity as a function of the field separation for both modified and nonmodified beams. Results are presented for various field configurations. Without the penumbra generator, lateral setup errors of 2-3 mm may introduce dose variations of 20% or more in the junction region. Similar setup errors cause less than 5% dose variations when the penumbra generator is used to match the fields. The potential of the technique for the irradiation of curved surfaces is presented. A possible method for implementing the modified penumbra into a conventional treatment planning system is evaluated.

An acute toxicity study on the effects of synchronous chemotherapy and radiotherapy in early stage breast cancer after conservative surgery

One hundred and ninety-seven patients with early stage breast cancer, who were treated initially with conservative surgery, were evaluated prospectively for acute toxicity after completing post-operative irradiation. Eighty-seven of these patients had synchronous chemotherapy with the 3M regimen (mitoxantrone, methotrexate and Mitomycin-C) during radiotherapy. The results indicate that patients receiving chemotherapy and radiotherapy (CRT) showed no significant difference in acute skin toxicity (AST) when compared with those treated with radiotherapy alone (RTO), with an odds ratio (OR = 0.6) and 95% confidence intervals (0.3-1.1) of developing either a moderate or severe, compared with a mild, skin reaction. Even after controlling for other confounding factors, such as treatment technique and beam energy, patients treated with the supine technique using 6-10 MV photons still displayed no significant difference in AST, with 12/74 (16%) patients in the CRT group and 14/66 (21%) in the RTO group developing a moderate or severe skin reaction (OR = 0.7 (95% CI 0.3-1.7)). Four of the 87 patients treated with CRT developed symptomatic acute radiation pneumonitis, three of whom were found to have > 3 cm of lung length on their simulator or check films. The volume of lung included within the treatment field was found to be statistically significant (P = 0.005) in predicting the onset of radiation pneumonitis in the CRT group. None of these patients has suffered any symptomatic late lung toxicity. We conclude that synchronous chemotherapy and radiotherapy, when using the 3M regimen, is feasible for patients having adjuvant treatment for early stage breast carcinoma and there is no significant increase in AST. However, it is associated with an increase in acute radiation pneumonitis when a significant volume of lung is included within the radiation treatment field.

A blended beam technique to decrease toxic effects of post mastectomy irradiation by combining and sequentially mixing electrons and photons

We studied 24 patients with Stage II or Stage III breast carcinoma, post total mastectomy, who had received adjuvant loco-regional irradiation (16 patients) or were irradiated for chest wall recurrence (8 patients), along with systemic chemotherapy and/or hormonotherapy. A technique is described for combining and sequentially mixing electron and photon beams. This blended beam method results in less severe acute and chronic skin reactions. Dose distribution to the chest wall and mediastinum are improved compared to the traditional photon-only techniques. At a median followup of four years our expected loco-regional control rates are not compromised. This technique is recommended for selected post mastectomy patients to reduce toxic effects of chest wall irradiation, particularly when chemotherapy lowers skin tolerance and the reserves of the heart, lung and bone marrow.

A practical alternative to conventional five-field irradiation postmastectomy for locally advanced breast cancer

A combination of electron and photon beams has been used as an alternative for the conventional five-field method to irradiate patients postmastectomy for locally advanced breast cancer. Anterior and posterior opposed photon beams treat in continuity the lateral chest wall, axilla, and supraclavicular lymph nodes. An adjacent anterior electron beam is used at an energy matched to the depth of the internal mammary nodes. It includes the anterior chest wall, but bolus is used in the lateral aspect to spare underlying lung. This electron beam eliminates the diverging junction between the internal mammary and medial tangential fields used in the conventional five-field technique. Overlaps along the junction between the photon and electron beams are minimized by placing the center of the photon field along its medial border. Measurements with an Alderson-Rando phantom show dose-distribution advantages for this technique over the conventional five-field approach. There is less chance of underdosing tumor cells or of overdosing normal tissue along beam junctions. Clinical studies on 29 patients treated by this technique between July 1985 and December 1989 show increased rates of acute skin reactions, but otherwise similar side effects compared with 57 breast cancer patients treated with the five-field technique over the same time period. Local recurrence rates and patient survival rates were similar for the two groups. Given the dose-distribution advantages of this technique and its simple adaptation to accommodate unusual surgical scars or cancer recurrences, its use should be considered for postmastectomy patients with locally advanced breast cancer in well-equipped cancer treatment centers.

Implementation of the three-field electron wraparound technique for extensive recurrent chest wall carcinoma: dosimetric and clinical considerations

Treatment of extensive recurrent chest wall carcinoma is a challenge for the radiation oncologist as well as the physics team responsible for setup, computer planning, and daily reproducibility. While electron arc therapy is desirable, unfortunately, most sites do not have this capability. The alternative method of treatment discussed here involves the use of a three-field electron wraparound technique for the chest wall when electron arc therapy is not available. This technique yields an excellent alternative treatment modality with flexibility to accommodate multiple electron energies to compensate for varying chest wall thickness. An additional anterior photon beam is used when skin lesions extend superiorly to the clavicle and along the proximal aspect of the arm. Computerized tomography (CT) interfaced radiotherapy computer planning is used to precisely calculate the sequential gantry angles, skin gaps for adjacent electron fields, and the appropriate junction moves to create a feathering effect of all overlap areas. Treatment aids include extensive shaping of electron and photon fields and the application of bolus material on all four fields. A Smithers Medical Products' Alpha Cradle is used to make this intricate setup possible, providing patient comfort and daily reproducibility for a more efficient treatment.