Intensity-modulated radiotherapy results in significant decrease in clinical toxicities compared with conventional wedge-based breast radiotherapy

Partial-volume segmentation for dose optimization in whole-breast radiotherapy: a comparative dosimetric and clinical analysis

PURPOSE

: To analyze the dosimetric and clinical benefit of a forward planned technique to optimize dose distribution in whole-breast irradation (WBI) using additional partial-volume segments (PVSeg).

PATIENTS AND METHODS

: In two separate treatment periods, 265 breast cancer patients received tangential-field WBI and were retrospectively analyzed. Between 02/2004 and 03/2006, 96 patients were treated with one to two additional low-weighted PVSeg to reduce dose peaks within the target volume. 169 patients treated between 01/2000 and 12/2001 before implementation of this PVSeg technique served as comparison group. Total dose was 50-50.4 Gy (single dose, 1.8-2 Gy). The planning target volume (PTV) receiving at least 95%, 105% and 110% of the reference dose (V(95-110%)) and frequency of moist skin desquamation during radiotherapy were compared uni- and multivariately with patient- and treatment-related variables.

RESULTS

: The mean PTV was 1,144 ml (range, 235-2,365 ml). Moist skin desquamations developed in 16 patients (17%) with PVSeg compared to 30 patients (18%) without PVSeg (p = 0.482). In breast volumes > 1,100 ml, the corresponding figures were 19% versus 29% (p = 0.133). V(105%) was significantly reduced by the use of PVSeg (82 +/- 51 ml vs. 143 +/- 129 ml; p < 0.0001). In univariate analysis, the following variables had significant influence on the development of moist skin desquamation: V(95%) (p < 0.0001), V(105%) (p < 0.001), V(110%) (p = 0.012) adjuvant chemotherapy (p = 0.02), and single dose (p = 0.009). In multivariate analysis, only V(95%) (p = 0.002) remained significant.

CONCLUSION

: The use of PVSeg in WBI reduced dose peaks within the PTV while breast volumes > 1,100 ml benefited most. V(95%) was strongly correlated to the risk of developing moist skin desquamations.

Tomotherapy and multifield intensity-modulated radiotherapy planning reduce cardiac doses in left-sided breast cancer patients with unfavorable cardiac anatomy

PURPOSE

For patients with left-sided breast cancers, radiation treatment to the intact breast results in high doses to significant volumes of the heart, increasing the risk of cardiac morbidity, particularly in women with unfavorable cardiac anatomy. We compare helical tomotherapy (TOMO) and inverse planned intensity modulated radiation therapy (IMRT) with three-dimensional conformal radiotherapy using opposed tangents (3D-CRT) for reductions in cardiac volumes receiving high doses.

METHODS AND MATERIALS

Fifteen patients with left-sided breast cancers and unfavorable cardiac anatomy, determined by a maximum heart depth (MHD) of >or=1.0 cm within the tangent fields, were planned for TOMO and IMRT with five to seven beam angles, in addition to 3D-CRT. The volumes of heart and left ventricle receiving >or=35 Gy (V35) were compared for the plans, as were the mean doses to the contralateral breast and the volume receiving >or=20 Gy (V20) for the ipsilateral lung.

RESULTS

The mean MHD was 1.7 cm, and a significant correlation was observed between MHD and both heart and left ventricle V35. The V35s for IMRT (0.7%) and TOMO (0.5%) were significantly lower than for 3D-CRT (3.6%). The V20 for IMRT (22%) was significantly higher than for 3D-CRT (15%) or TOMO (18%), but the contralateral breast mean dose for TOMO (2.48 Gy) was significantly higher than for 3D-CRT (0.93 Gy) or IMRT (1.38 Gy).

CONCLUSIONS

Both TOMO and IMRT can significantly reduce cardiac doses, with modest increases in dose to other tissues in left-sided breast cancer patients with unfavorable cardiac anatomy.

A nationwide survey of radiation oncologists' management practices of radiation-induced skin reaction (RISK)

Purpose:A questionnaire was developed to explore variations among radiation oncologists in managing early-stage breast cancer, specifically radiation-induced skin reaction (RISK).

Materials and methods:A survey was designed to target a database of 962 radiation oncologists, self-identified as ‘interested in treatment of breast cancer’. This database was obtained from the American Society of Therapeutic Radiology & Oncology (ASTRO). Participants submitted the survey online or by mail. Overall response to the survey was 282 out of 962 (29.3%). Data were handled as rates.

Results:Out of 282 respondents, 275 (97.5%) agreed on delivering 4500–5040 cGy. The most frequently employed dose was 5040/180 cGy. Three-dimensional-conformal (3DCRT) treatment was used by 55.4%, intensity-modulated radiotherapy (IMRT) by 24.5%, and conventional by 20.1%. Almost all (92.5%) agreed on using boost in ductal carcinoma in situ (DCIS). Image-guided boost placement (IGBP) was used by 87.3%. Boost dose included variations: 50.2, 7.3, and 18% used 1000, 1200, and 1400 cGy, respectively; the remaining used higher doses. In management of RISK, Aquaphor was the most popular agent (72.1%). Other agents were utilized either alone or in combination. Almost all (99%) agreed that large breast size increases RISK.

Conclusion:This survey offers a glimpse of management practices in early-stage breast cancer amongst a cross-section of radiation oncologists in the United States. Although there appears to be an overall congruence on the doses and techniques of radiation delivery, the management of RISK is varied. Additional efforts are warranted to standardize practices in order to practice evidence based medicine in a cost-effective manner.

Breast intensity-modulated radiation therapy reduces time spent with acute dermatitis for women of all breast sizes during radiation

PURPOSE

To study the time spent with radiation-induced dermatitis during a course of radiation therapy for breast cancer in women treated with conventional or intensity-modulated radiation therapy (IMRT).

METHODS AND MATERIALS

The study population consisted of 804 consecutive women with early-stage breast cancer treated with breast-conserving surgery and radiation from 2001 to 2006. All patients were treated with whole-breast radiation followed by a boost to the tumor bed. Whole-breast radiation consisted of conventional wedged photon tangents (n = 405) earlier in the study period and mostly of photon IMRT (n = 399) in later years. All patients had acute dermatitis graded each week of treatment.

RESULTS

The breakdown of the cases of maximum acute dermatitis by grade was as follows: 3%, Grade 0; 34%, Grade 1; 61%, Grade 2; and 2%, Grade 3. The breakdown of cases of maximum toxicity by technique was as follows: 48%, Grade 0/1, and 52%, Grade 2/3, for IMRT; and 25%, Grade 0/1, and 75%, Grade 2/3, for conventional radiation therapy (p < 0.0001). The IMRT patients spent 82% of weeks during treatment with Grade 0/1 dermatitis and 18% with Grade 2/3 dermatitis, compared with 29% and 71% of patients, respectively, treated with conventional radiation (p < 0.0001). Furthermore, the time spent with Grade 2/3 toxicity was decreased in IMRT patients with small (p = 0.0015), medium (p < 0.0001), and large (p < 0.0001) breasts.

CONCLUSIONS

Breast IMRT is associated with a significant decrease both in the time spent during treatment with Grade 2/3 dermatitis and in the maximum severity of dermatitis compared with that associated with conventional radiation, regardless of breast size.

Planning and delivery of intensity-modulated radiation therapy

Intensity modulated radiation therapy (IMRT) is an advanced form of external beam radiation therapy. IMRT offers an additional dimension of freedom as compared with field shaping in three-dimensional conformal radiation therapy because the radiation intensities within a radiation field can be varied according to the preferences of locations within a given beam direction from which the radiation is directed to the tumor. This added freedom allows the treatment planning system to better shape the radiation doses to conform to the target volume while sparing surrounding normal structures. The resulting dosimetric advantage has shown to translate into clinical advantages of improving local and regional tumor control. It also offers a valuable mechanism for dose escalation to tumors while simultaneously reducing radiation toxicities to the surrounding normal tissue and sensitive structures. In less than a decade, IMRT has become common practice in radiation oncology. Looking forward, the authors wonder if IMRT has matured to such a point that the room for further improvement has diminished and so it is pertinent to ask what the future will hold for IMRT. This article attempts to look from the perspective of the current state of the technology to predict the immediate trends and the future directions. This article will (1) review the clinical experience of IMRT; (2) review what we learned in IMRT planning; (3) review different treatment delivery techniques; and finally, (4) predict the areas of advancements in the years to come.

Hypofractionated Breast and Chest Wall Irradiation Using Simultaneous in-field Boost IMRT Delivered via Helical Tomotherapy

Although helical tomotherapy has been described as a means of administering accelerated partial breast irradiation, its practicality in routine whole breast irradiation as part of breast conserving therapy or chest wall irradiation has been questioned. In this technical note we describe our method of whole breast or chest wall irradiation using helical tomotherapy based image-guided, hypofractionated, simultaneous in-field boost intensity modulated radiation therapy.

We have observed that excellent dose-distributions can be achieved with helical tomotherapy through a careful selection of treatment planning parameters. Dose homogeneity to the whole breast and simultaneously targeted lumpectomy region appears superior to conventional “tangents” with minimal hot or cold spots. Dose-volume histogram analysis documents effective reduction of high dose to critical sensitive structures (heart and lung) although a greater volume of these non-target organs receives low dose compared to what is typical with tangential beams. Treatment planning is efficient and is usually completed within one to two hours, although physician contouring requires more time and attention than non-IMRT approaches. Pretreatment megavoltage CT (MVCT) imaging has proved invaluable in aiding set-up and engenders greater confidence that the planned IMRT dose distributions are truly being delivered. In some situations, MVCT can provide visual feedback when a seroma or overall breast volume has changed significantly since simulation, thereby identifying cases where replanning might be prudent. Treatment is brief, typically completed in 6 to 9 minutes.

Initial clinical application has confirmed the feasibility and practicality of helical tomotherapy as an efficient means of administering radiation therapy for routine breast-conserving therapy and post-mastectomy chest wall irradiation. A simultaneous in-field boost technique reduces the length of the overall course by about a week thereby adding convenience and reducing costs. Further refinements of our technique are being explored and formal prospective clinical evaluation is underway.

Phase I-II studies on accelerated IMRT in breast carcinoma: technical comparison and acute toxicity in 332 patients

BACKGROUND AND PURPOSE

To evaluate the results in terms of dosimetric parameters and acute toxicity of two clinical studies (MARA-1 and MARA-2) on accelerated IMRT-based postoperative radiotherapy. These results are compared with historical control group (CG) of patients treated with "standard" 3D postoperative radiotherapy.

MATERIALS AND METHODS

Prescribed dose to the breast was 50.4Gy in the CG, 40Gy in MARA-1 (low risk of local recurrence), and 50Gy in MARA-2 (medium-high risk of recurrence). The tumor bed total dose was 60.4Gy (sequential 10Gy electron boost), 44Gy (concomitant 4Gy boost), and 60Gy (concomitant 10Gy boost) in CG, MARA-1 and MARA-2 studies, respectively. Overall treatment time was of 32 fractions for CG (6.4weeks); 16 fractions for MARA-1 study (3.2weeks) and 25 fractions for MARA-2 study (5weeks).

RESULTS

Three hundred and thirty two patients were included in the analysis. Dosimetric analysis showed D(max) and V(107%) reduction (p<0.001) and D(min) improvement (p<0.001) in the PTV in patients treated with IMRT. Grade 2 acute skin toxicity was 33.6%, 13.1%, and 45.1% in the CG, MARA-1, and MARA-2, respectively (p<0.001), and grade 3 acute skin toxicity was 3.1%, 1.0%, and 2.0%, respectively. Similarly, larger PTV and use of chemotherapy with anthracyclines and taxanes were associated with a greater acute toxicity. With a median follow-up of 31 months, no patients showed local or nodal relapse.

CONCLUSIONS

A simplified step and shoot IMRT technique allowed better PTV coverage and reduced overall treatment time (CG, 6.6weeks; MARA-1, 3.2weeks; MARA-2, 5weeks) with acceptable short-term toxicity.

Symptom management in premenopausal patients with breast cancer

Women with breast cancer have many adverse symptoms, of which some are specific to premenopausal patients. Management of these common symptoms include non-hormonal drugs, such as antidepressants and antiseizure compounds to alleviate hot flushes. Non-oestrogenic vaginal lubricants seem to moderately decrease occurrence of vaginal dryness and dyspareunia. Transdermal testosterone alone has not been shown to improve libido in these women. Options for fertility preservation include cryopreservation of embryos or oocytes before chemotherapy. Exercise is the one evidenced-based intervention shown to positively affect cancer-related fatigue. However, effective prevention and treatments for peripheral neuropathy and paclitaxel acute pain syndrome remain elusive. Weight-bearing exercise helps to maintain bone strength with adequate intake of calcium and vitamin D. Use of bisphosphonates in women taking aromatase inhibitors (combined with ovarian suppression in premenopausal women) to prevent bone fractures has not been substantiated, although it should be considered in women with osteoporosis. No specific drug has been shown to prevent radiation-induced dermatitis alone. Although some effective treatments can counteract symptoms related to cancer or treatments, research is needed to expand evidence-based care in premenopausal survivors of breast cancer.

Evidence behind use of intensity-modulated radiotherapy: a systematic review of comparative clinical studies

Since its introduction more than a decade ago, intensity-modulated radiotherapy (IMRT) has spread to most radiotherapy departments worldwide for a wide range of indications. The technique has been rapidly implemented, despite an incomplete understanding of its advantages and weaknesses, the challenges of IMRT planning, delivery, and quality assurance, and the substantially increased cost compared with non-IMRT. Many publications discuss the theoretical advantages of IMRT dose distributions. However, the key question is whether the use of IMRT can be exploited to obtain a clinically relevant advantage over non-modulated external-beam radiation techniques. To investigate which level of evidence supports the routine use of IMRT for various disease sites, we did a review of clinical studies that reported on overall survival, disease-specific survival, quality of life, treatment-induced toxicity, or surrogate endpoints. This review shows evidence of reduced toxicity for various tumour sites by use of IMRT. The findings regarding local control and overall survival are generally inconclusive.

Long-term outcomes of IMRT for breast cancer: a single-institution cohort analysis

PURPOSE

To evaluate long-term outcomes of adjuvant breast intensity-modulated radiation therapy (IMRT), with a comparison cohort receiving conventional radiation (cRT) during the same period.

METHODS AND MATERIALS

Retrospective review identified patients with Stages 0-III breast cancer who underwent irradiation after conservative surgery from January 1999 to December 2003. Computed tomography simulation was used to design standard tangential breast fields with enhanced dynamic wedges for cRT and both enhanced dynamic wedges and dynamic multileaf collimators for IMRT. Patients received 1.8-2-Gy fractions to 44-50.4 Gy to the whole breast, followed by an electron boost of 10-20 Gy.

RESULTS

A total of 245 breasts were treated in 240 patients: 121 with IMRT and 124 with cRT. Median breast dose was 50 Gy, and median total dose was 60 Gy in both groups. Patient characteristics were well balanced between groups. Median follow-ups were 6.3 years (range, 3.7-104 months) for patients treated with IMRT and 7.5 years (range, 4.9-112 months) for those treated with cRT. Treatment with IMRT decreased acute skin toxicity of Radiation Therapy Oncology Group Grade 2 or 3 compared with cRT (39% vs. 52%; p = 0.047). For patients with Stages I-III (n = 199), 7-year Kaplan-Meier freedom from ipsilateral breast tumor recurrence (IBTR) rates were 95% for IMRT and 90% for cRT (p = 0.36). For patients with Stage 0 (ductal carcinoma in situ, n = 46), 7-year freedom from IBTR rates were 92% for IMRT and 81% for cRT (p = 0.29). Comparing IMRT with cRT, there were no statistically significant differences in overall survival, disease-specific survival, or freedom from IBTR, contralateral breast tumor recurrence, distant metastasis, late toxicity, or second malignancies.

CONCLUSIONS

Patients treated with breast IMRT had decreased acute skin toxicity, and long-term follow-up shows excellent local control similar to a contemporaneous cohort treated with cRT.

Improvement in dose homogeneity with electronic tissue compensation over IMRT and conventional RT in whole brain radiotherapy

BACKGROUND AND PURPOSE

To perform a dosimetric analysis of whole brain radiotherapy using electronic tissue compensation (ECOMP) with dynamic multileaf collimation (dMLC) and its comparisons with inverse-planned intensity modulated radiation therapy (IMRT) with optimization constraints and conventional whole brain radiotherapy (WBRT).

MATERIALS AND METHODS

Ten patients (6 adult, 4 pediatric) who were treated at our institution were selected for this study. WBRT fields were defined using opposed lateral fields directed at the intracranial contents and MLC leaves were used to block the critical normal structures. A two-field inverse-planned IMRT plan was then developed using sliding window technique and two optimization constraints. Finally, a dMLC plan with electronic tissue compensation (ECOMP) was developed using identical beam and collimator angles and blocking strategy; the fluence map was generated based on tissue compensation and no additional constraints were given for optimization purposes. This tissue compensation based fluence map was applied to deliver a homogenous dose to the intracranial contents. Radiation dose was identically prescribed to the isocenter (30.0 Gy in 10 fractions) for all the cases. A dosimetric comparison was then performed for each method in our patient population.

RESULTS

ECOMP significantly reduced the mean maximum dose (D(max)) to the intracranial contents as compared to both WBRT (103.9% vs. 112.4%, p<0.0001) and IMRT (106.1%, p=0.02). ECOMP also reduced the intracranial volume receiving greater than 103% of the prescribed dose (2.6% vs. 54.9%, p<0.0001) and the intracranial volume receiving greater than 105% of the prescribed dose (0% vs. 26%, p<0.0001) as compared to WBRT; there was no statistical difference in these two parameters between ECOMP and IMRT. The mean number of monitor units was increased, however, using both ECOMP and IMRT as compared to WBRT (870 and 860 vs. 318, p<0.0001).

CONCLUSIONS

Dynamic multileaf collimation with electronic tissue compensation (ECOMP) leads to improved dose homogeneity with less 'hot spots' as compared to conventional and inverse-planned intensity modulated whole brain radiotherapy. At our institution, ECOMP is being used in all pediatric patients or select adult patients with a long life expectancy requiring cranial radiotherapy.

Intensity-modulated radiotherapy for resected mesothelioma: the Duke experience

PURPOSE

To assess the safety and efficacy of intensity-modulated radiotherapy (IMRT) after extrapleural pneumonectomy for malignant pleural mesothelioma.

METHODS AND MATERIALS

Thirteen patients underwent IMRT after extrapleural pneumonectomy between July 2005 and February 2007 at Duke University Medical Center. The clinical target volume was defined as the entire ipsilateral hemithorax, chest wall incisions, including drain sites, and involved nodal stations. The dose prescribed to the planning target volume was 40-55 Gy (median, 45). Toxicity was graded using the modified Common Toxicity Criteria, and the lung dosimetric parameters from the subgroups with and without pneumonitis were compared. Local control and survival were assessed.

RESULTS

The median follow-up after IMRT was 9.5 months. Of the 13 patients, 3 (23%) developed Grade 2 or greater acute pulmonary toxicity (during or within 30 days of IMRT). The median dosimetric parameters for those with and without symptomatic pneumonitis were a mean lung dose (MLD) of 7.9 vs. 7.5 Gy (p = 0.40), percentage of lung volume receiving 20 Gy (V(20)) of 0.2% vs. 2.3% (p = 0.51), and percentage of lung volume receiving 5 Gy (V(20)) of 92% vs. 66% (p = 0.36). One patient died of fatal pulmonary toxicity. This patient received a greater MLD (11.4 vs. 7.6 Gy) and had a greater V(20) (6.9% vs. 1.9%), and V(5) (92% vs. 66%) compared with the median of those without fatal pulmonary toxicity. Local and/or distant failure occurred in 6 patients (46%), and 6 patients (46%) were alive without evidence of recurrence at last follow-up.

CONCLUSIONS

With limited follow-up, 45-Gy IMRT provides reasonable local control for mesothelioma after extrapleural pneumonectomy. However, treatment-related pulmonary toxicity remains a significant concern. Care should be taken to minimize the dose to the remaining lung to achieve an acceptable therapeutic ratio.

Radiation therapy using a simultaneously integrated boost for early-stage breast cancer

Evaluation of: van der Laan HP, Dolsma WV, Maduro JH et al.: Three-dimensional conformal simultaneously integrated boost technique for breast-conserving therapy. Int. J. Radiat. Oncol. Biol. Phys. 68(4), 1018–1023 (2007). Radiotherapy of 25 daily fractions of 2 Gy after breast-conserving surgery is effective in reducing the risk of a local recurrence. An extra boost dose of eight daily fractions of 2 Gy reduces this risk even further by a factor of 1.7. However, the extended treatment time is not patient friendly and is more labor intensive. With new, advanced equipment, it is now possible to use a so-called simultaneous integrated boost (SIB) technique to prevent these downsides. With this technique, the boost dose is integrated into the standard dose fractions, thus reducing the number of times a patient has to be irradiated. However, the initial implementation of this technique is very labor intensive and requires profound knowledge of the radiotherapy treatment planning system and treatment unit. In their article, van der Laan and colleagues present an SIB technique which is easier to implement than a sophisticated (inversely planned) SIB technique. Moreover, they are the first authors to present data on acute skin toxicity using this technique and fractionation schedule. Their work contributes significantly to the efforts of clinical physicists, radiation oncologists and radiation therapists worldwide to improve breast cancer patient care by the safe implementation of new, advanced radiotherapy technology. However, one has to realize that implementing such a technique still requires accurate knowledge of the target volume delineation and patient set-up accuracy in each institution. Also, boost volume changes may occur during treatment, which must be taken into account. Data are becoming available on this, and clinical trials investigating even higher boost doses or more conformal treatment techniques are being conducted.