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

PURPOSE

We have previously demonstrated that intensity-modulated radiotherapy (IMRT) with a static multileaf collimator process results in a more homogenous dose distribution compared with conventional wedge-based whole breast irradiation (WBI). In the present analysis, we reviewed the acute and chronic toxicity of this IMRT approach compared with conventional wedge-based treatment.

METHODS AND MATERIALS

A total of 172 patients with Stage 0-IIB breast cancer were treated with lumpectomy followed by WBI. All patients underwent treatment planning computed tomography and received WBI (median dose, 45 Gy) followed by a boost to 61 Gy. Of the 172 patients, 93 (54%) were treated with IMRT, and the 79 patients (46%) treated with wedge-based RT in a consecutive fashion immediately before this cohort served as the control group. The median follow-up was 4.7 years.

RESULTS

A significant reduction in acute Grade 2 or worse dermatitis, edema, and hyperpigmentation was seen with IMRT compared with wedges. A trend was found toward reduced acute Grade 3 or greater dermatitis (6% vs. 1%, p = 0.09) in favor of IMRT. Chronic Grade 2 or worse breast edema was significantly reduced with IMRT compared with conventional wedges. No difference was found in cosmesis scores between the two groups. In patients with larger breasts (> or =1,600 cm(3), n = 64), IMRT resulted in reduced acute (Grade 2 or greater) breast edema (0% vs. 36%, p <0.001) and hyperpigmentation (3% vs. 41%, p = 0.001) and chronic (Grade 2 or greater) long-term edema (3% vs. 30%, p = 0.007).

CONCLUSION

The use of IMRT in the treatment of the whole breast results in a significant decrease in acute dermatitis, edema, and hyperpigmentation and a reduction in the development of chronic breast edema compared with conventional wedge-based RT.

Correlating metabolic and anatomic responses of primary lung cancers to radiotherapy by combined F-18 FDG PET-CT imaging

Background

To correlate the metabolic changes with size changes for tumor response by concomitant PET-CT evaluation of lung cancers after radiotherapy.

Methods

36 patients were studied pre- and post-radiotherapy with¹⁸FDG PET-CT scans at a median interval of 71 days. All of the patients were followed clinically and radiographically after a mean period of 342 days for assessment of local control or failure rates. Change in size (sum of maximum orthogonal diameters) was correlated with that of maximum standard uptake value (SUV) of the primary lung cancer before and after conventional radiotherapy.

Results

There was a significant reduction in both SUV and size of the primary cancer after radiotherapy (p < 0.00005). Among the 20 surviving patients, the sensitivity, specificity, and accuracy using PET (SUV) were 94%, 50%, 90% respectively and the corresponding values using and CT (size criteria) were 67%, 50%, and 65% respectively. The metabolic change (SUV) was highly correlated with the change in size by a quadratic function. In addition, the mean percentage metabolic change was significantly larger than that of size change (62.3 ± 32.7% vs 47.1 ± 26.1% respectively, p = 0.03)

Conclusion

Correlating and incorporating metabolic change by PET into size change by concomitant CT is more sensitive in assessing therapeutic response than CT alone.

The use of molecular assays to establish definitively the clonality of ipsilateral breast tumor recurrences and patterns of in-breast failure in patients with early-stage breast cancer treated with breast-conserving therapy

BACKGROUND

Results from numerous trials have indicated that breast-conserving therapy (BCT) produces outcomes equivalent to those produced by mastectomy in terms of both locoregional control and survival. However, conservative treatment has resulted in the dilemma of how best to address recurrences when they appear in a breast treated previously with radiation therapy. Attempts have been made to characterize ipsilateral breast tumor recurrences (IBTRs) as either true recurrences of the treated malignancy or new primary carcinomas, because cancers that represent new primary tumors may be associated with a more favorable prognosis compared with cancers that represent true recurrences.

METHODS

The authors studied the clonality of IBTRs relative to the initial invasive carcinomas by using a polymerase chain reaction loss-of-heterozygosity molecular comparison assay in 29 patients who received breast-conserving therapy (BCT).

RESULTS

Twenty-two IBTRs (76%) were related clonally to the initial carcinoma, and 7 IBTRs (24%) were clonally different. Clonally related IBTRs were more frequently higher grade (72.2% vs 14.3%; P = .009) and developed sooner after initial treatment (mean time to IBTR, 4.04 years in clonally related IBTRs vs 9.25 years in clonally different IBTRs; P = .002). Six patients subsequently developed distant metastases, and 5 of those patients (83.3%) had clonally related IBTRs. Clinical IBTR classification and molecular clonality assay results differed in 30% of all patients. The proportion of IBTRs that were related clonally at 5 years, 10 years, and 15 years after BCT were 93%, 67%, and 33%, respectively.

CONCLUSIONS

Clinical classifications of IBTRs were unreliable methods for determining clonality in many patients. Molecular clonality assays provided a reliable means of identifying patients who may benefit from aggressive systemic therapy at the time of IBTR and also provided a more accurate assessment of the efficacy of various forms of local therapy.

Long-term efficacy and patterns of failure after accelerated partial breast irradiation: a molecular assay-based clonality evaluation

PURPOSE

To determine the long-term efficacy and cosmetic results of accelerated partial breast irradiation (APBI) by reviewing our institution's experience.

METHODS AND MATERIALS

A total of 199 patients with early-stage breast cancer were treated prospectively with adjuvant APBI after lumpectomy using interstitial brachytherapy. All patients had negative margins, 82% had Stage I disease, median tumor size was 1.1 cm, and 12% had positive lymph nodes. The median follow-up for surviving patients was 8.6 years. Fifty-three patients (27%) have been followed for >or=10 years.

RESULTS

Six ipsilateral breast tumor recurrences (IBTRs) were observed, for a 5-year and 10-year actuarial rate of 1.6% and 3.8%, respectively. A total of three regional nodal failures were observed, for a 10-year actuarial rate of 1.6%. Five contralateral breast cancers developed, for a 5- and 10-year actuarial rate of 2.2% and 5.2%, respectively. The type of IBTR (clonally related vs. clonally distinct) was analyzed using a polymerase chain reaction-based loss of heterozygosity assay. Eighty-three percent of IBTRs (n = 5) were classified as clonally related. Multiple clinical, pathologic, and treatment-related factors were analyzed for an association with the development of an IBTR, regional nodal failure, or contralateral breast cancer. On multivariate analysis, no variable was associated with any of these events. Cosmetic results were rated as excellent/good in 99% of patients.

CONCLUSIONS

Long-term results with APBI using interstitial brachytherapy continue to demonstrate excellent long-term local and regional control rates and cosmetic results. According to a polymerase chain reaction-based loss of heterozygosity assay, 83% of recurrences were classified as clonally related.

A multicenter study demonstrating discordant results from electronic prostate-specific antigen biochemical failure calculation systems

PURPOSE

To evaluate the interobserver variation of four electronic biochemical failure (bF) calculators using three bF definitions.

METHODS AND MATERIALS

The data of 1200 men were analyzed using the electronic bF calculators of four institutions. Three bF definitions were examined for their concordance of bF identification across the centers: the American Society for Therapeutic Radiology and Oncology consensus definition (ACD), the lowest prostate-specific antigen (PSA) level to date plus 2 ng/mL (L2), and a threshold of 3 ng/mL (T3).

RESULTS

Unanimous agreement regarding bF status using the ACD, L2, and T3 definitions occurred in 87.3%, 96.4%, and 92.7% of cases, respectively. Using the ACD, 63% of the variation was from one institution, which allowed the bF status to be reversed if a PSA decline was seen after bF (PSA "bounce"). A total of 270 men had an ACD bF time variation of >2 months across the calculators, and the 5-year freedom from bF rate was 49.8-60.9%. The L2 definition had a 20.5% rate of calculated bF times; which varied by >2 months (median, 6.4; range, 2.1-75.6) and a corresponding 5-year freedom from bF rate of 55.9-61.0%. The T3 definition had a 2.0% range in the 5-year freedom from bF. Fifteen definition interpretation variations were identified.

CONCLUSION

Reported bF results vary not only because of bF definition differences, but because of variations in how those definitions are written into computer-based calculators, with multiple interpretations most prevalent for the ACD. An algorithm to avoid misinterpretations is proposed for the L2 definition. A verification system to guarantee consistent electronic bF results requires development.

Addressing glucose sensitivity measured by F-18 FDG PET in lung cancers for radiation treatment planning and monitoring

PURPOSE

To address glucose sensitivity in lung cancers before and after radiation treatment (Tx).

METHODS AND MATERIALS

Twelve patients were each studied with two pre-Tx positron emission tomography (PET) scans and 3 patients each with one post-Tx PET scan, with glucose concentration [Glc] and maximum standard uptake value (SUV) recorded. The pre-Tx glucose sensitivity, g from SUV1/SUV2= {[Glc]1/[Glc]2}g and Tx index, tau from SUVpost-Tx/SUVpre-Tx = {[Glc]post-Tx/[Glc]pre-Tx}tau was calculated by linear regression. Pre-Tx SUVs were corrected to post-Tx Glc with g (SUV'pre-Tx) for a pure Tx effect, R = ln(SUVpost-Tx/SUV'pre-Tx).

RESULTS

There were no significant differences in SUV but [Glc] were different (96.4 +/- 10.9 vs. 88.3 +/- 10.5, p = 0.015) between two pre-Tx PET scans. Linear regression yielded g = -0.79 and tau = -1.78 to -2.41 (p < 0.0005 in all). The %DeltaSUV after Tx for 3 patients without vs. with g correction were different by -12%, 0%, and + 7%, suggesting varying effects from glucose. R values were also different and mean R (-0.81 +/- 0.38) was significantly different from zero (p = 0.03), consistent with successful Tx as confirmed by clinico-radiologic follow-up.

CONCLUSIONS

The extra dimension of glucose sensitivity, g besides SUV incorporated in the combined Tx-derived tau may be a useful global Tx evaluation index even with differing [Glc].

Changes in the respiratory pattern during radiotherapy for cancer in the lung

BACKGROUND AND PURPOSE

To quantify changes in patients' diaphragm motion pattern over the course of radiotherapy and to evaluate the implications of these changes for 4D radiotherapy.

PATIENTS AND METHODS

From January 2004 to October 2004, 10 patients with lung malignancies treated at our department underwent weekly respiratory motion verification during the course of external beam radiation. An onboard kilovoltage imaging system was used to acquire fluoroscopy weekly for patients with lung neoplasms. The diaphragm position as a function of time was extracted automatically from the fluoroscopy and used to calculate the daily mean and daily SD of motion. The diaphragm position was related to both a bony reference point and machine isocenter. Changes in the daily mean and daily SD in relation to the reference (first day) daily mean and reference daily SD were measured.

RESULTS

The mean change in the daily mean was 0.32 mm+/-6.11 mm in relation to the bony reference point and 0.38 mm+/-6.28 mm in relation to isocenter. The mean change in the daily SD was 0.91 mm+/-1.81 mm. The mean systematic change in the daily mean was 4.97 mm, and the mean random change in the daily mean was 3.61 mm.

CONCLUSIONS

Daily verification of 4D radiotherapy techniques to assess the necessity of online set-up correction may be required due to the large change in the mean diaphragm position observed for these patients. However, the variation of the daily SD was small for most patients. Adaptive adjustment of the margin may be necessary for those patients with larger variation of the daily SD.

Factors associated with local recurrence and cause-specific survival in patients with ductal carcinoma in situ of the breast treated with breast-conserving therapy or mastectomy

PURPOSE

We reviewed our institution's experience treating patients with ductal carcinoma in situ (DCIS) of the breast to determine risk factors for ipsilateral breast tumor recurrence (IBTR) and cause-specific survival (CSS) after breast-conserving therapy (BCT) or mastectomy.

MATERIALS AND METHODS

Between 1981 and 1999, 410 cases of DCIS (405 patients) were treated at our institution; 367 were managed with breast-conserving surgery (54 with lumpectomy alone and 313 with adjuvant radiation therapy (RT) [median dose, 45 Gy]). Of these 313 patients, 298 received also a supplemental boost of RT to the lumpectomy cavity (median dose, 16 Gy). Forty-three patients underwent mastectomy; 2 (5%) received adjuvant RT to the chest wall. A true recurrence/marginal miss (TR/MM) IBTR was defined as failure within or adjacent to the tumor bed in patients undergoing BCT. Median follow-up for all patients was 7 years (mean: 6.1 years).

RESULTS

Thirty patients (8.2%) experienced an IBTR after BCT (25 [8%] after RT, 5 [9.3%] after no RT), and 2 patients (4.7%) developed a chest wall recurrence after mastectomy. Of the 32 local failures, 20 (63%) were invasive (18/30 [60%] after BCT and 2/2 [100%] after mastectomy), and 37% were DCIS alone. Twenty-four (80%) of the IBTRs were classified as TR/MM. The 10-year freedom from local failure, CSS, and overall survival after BCT or mastectomy were 89% vs. 90% (p = 0.4), 98% vs. 100% (p = 0.7), and 89% vs. 100% (p = 0.3), respectively. Factors associated with IBTR on Cox multivariate analysis were younger age (p = 0.02, hazard ratio [HR] 1.06 per year), electron boost energy < or = 9 MeV (p = 0.03, HR 1.41), final margins < or = 2 mm (p = 0.007; HR, 3.65), and no breast radiation (p = 0.002, HR 5.56). On Cox univariate analysis for BCT patients, IBTR, TR/MM failures, and predominant nuclear Grade 3 were associated with an increased risk of distant metastases and a reduced CSS.

CONCLUSIONS

After treatment for DCIS, 10-year rates of local control, CSS, and overall survival were similar after mastectomy and BCT. Young age (<45 years), close/positive margins (< or = 2 mm), no breast radiation, and lower electron boost energies (< or = 9 MeV) were associated with IBTR. Local failure and predominant nuclear Grade 3 were found to have a small (4%-12%) but statistically significantly negative impact on the rates of distant metastasis and CSS. These results suggest that optimizing local therapy (surgery and radiation) is crucial to improve local control and CSS in patients treated with DCIS.

Computed Tomography Guided Management of Interfractional Patient Variation

Interfractional patient variation occurs regularly and considerably during the radiotherapy course. Consequently, a generic but large planning target margin has to be applied when patient treatment plan design based on a single pre-treatment computed tomography scan is used to guide multifraction radiation treatment, which creates a major limiting factor for radiotherapy improvement. Planning target margins can be significantly reduced using multiple (or 4-dimensional) image feedback management in the routine treatment process. The most effective method in multiple-image feedback management of radiotherapy is the adaptive control methodology. The adaptive radiotherapy technique aims to customize each patient's treatment plan to patient-specific variation by evaluating and characterizing the systematic and random variations through image feedback and including them in adaptive planning. Adaptive radiotherapy will become a new treatment standard, in which a predesigned adaptive treatment strategy, including the schedules of imaging and replanning, will eventually replace the predesigned treatment plan in the routine clinical practice.

LIMITATIONS IN THE USE OF SERUM PROSTATE SPECIFIC ANTIGEN LEVELS TO MONITOR PATIENTS AFTER TREATMENT FOR PROSTATE CANCER

PURPOSE

We reviewed the literature to help clarify the benefits and/or hazards associated with monitoring serum prostate specific antigen (PSA) after treatment with surgery or radiation therapy (RT) for nonmetastatic prostate cancer.

MATERIALS AND METHODS

A search was performed for 1990 to 2004 using the MEDLINE database, CancerLit database and reference lists of relevant studies to obtain articles addressing the use of serum PSA to follow patients after treatment for prostate cancer. Studies were reviewed to determine 1) if serial PSA monitoring provides an early and accurate surrogate assessment of cancer cure or treatment failure, 2) if any pattern in the PSA profile after treatment provides conclusive evidence of early local vs systemic failure, 3) the magnitude of the lead time to clinical failure that serial PSA monitoring may provide and 4) if the early identification of biochemical failure (BF) with earlier intervention improves outcome.

RESULTS

Although a lower PSA nadir after treatment with RT has been associated with cancer cure, 5% to 25% of patients ultimately have failure (beyond 5 years) even with the most optimal biochemical response. The most appropriate BF definitions to use after treatment for prostate cancer with RT remains controversial due to substantial differences in their accuracy, sensitivity, specificity and positive predictive value for clinical outcome. No pattern of PSA kinetics after treatment has conclusively been associated with a specific recurrence site. Biochemical failure definitions in patients treated with RT appear to provide a 6 to 18 month lead time to clinical failure but there are only limited published data to suggest that early intervention of any type (androgen deprivation, RT, surgery, etc) impacts survival.

CONCLUSIONS

The overall benefit of monitoring serum PSA after treatment for prostate cancer remains controversial. Considering the potential dangers associated with incorrectly assuming the efficacy of new forms of treatment, the toxicity of administering salvage therapies of uncertain efficacy after BF has been identified and the anxiety associated with tracking posttreatment serum PSA, additional studies must be done to determine the appropriate use of this marker in properly treating patients after therapy.

Surgical considerations in the treatment of early stage breast cancer with accelerated partial breast irradiation (APBI) in breast conserving therapy via intersitial brachytherapy

OBJECTIVE

To examine early and late toxicities, evaluate cosmetic results, and determine the need for reoperation or additional diagnostic procedures in patients treated with accelerated partial breast irradiation (APBI) delivered by way of an interstitial implant in breast-conserving therapy.

METHODS

A total of 199 patients with stage I or II breast cancer were managed with lumpectomy followed by radiation restricted to the tumor bed using an interstitial implant (APBI). Retrospective analyses were performed for early and late toxicities (infection, fat necrosis, breast pain, edema, erythema, fibrosis, pigmentation changes, and telangiectasias), need for reoperation or additional diagnostic procedures, cosmetic results, and local control. Patient selection criteria by the surgeon for referral to RT for APBI included age, tumor size, histology, nodal status, margin status, and absence of extensive intraductal component. Treatment was delivered with either a low-dose or high-dose rate implant. Median follow-up was 5.7 years, and 54% of the patients were followed-up for >7 years.

RESULTS

Infections developed in 22 of 199 (11%) patients: 7% early (</=1 month after implant removal) and 4% late (>1 month after implant removal). Five of the 22 patients (2% of all patients) required operative intervention for the infection, either incision and drainage or debridement. There was a statistically significant difference between infection rates with open (8.5%) versus closed (2.5%) cavity placement of the interstitial needles (P = 0.005). There was no statistically significant difference between low-dose rate (inpatient) and high-dose rate (outpatient) treatment (P = 0.207). Forty-five patients (23%) had an additional diagnostic procedure to evaluate a suspicious or uncertain finding on physical examination or mammogram. Fibrosis and fat necrosis were found in 26 of the 45 patients. The incidence of fat necrosis increased with time. More patients were found to have fat necrosis after 5 years. One patient had fat necrosis diagnosed at <6 months; 8 patients (4% of total) at >/=6 months to <2 years; 10 patients (5% of total) at >/=2 years to <5 years; and 22 patients (11% of total) at >/=5 years. The majority of fat necrosis was detected on mammogram (80%) and was asymptomatic (78%). Cosmesis and toxicities were assessed at 3 defined time points: </=6 months, 2 years, and >/=5 years of follow-up. Using Harvard criteria, good to excellent cosmetic results were observed in >90% of patients. Breast pain, edema, and erythema diminished with time. Of the 199 cases, there were only 5 ipsilateral breast failures, yielding a 5-year actuarial local recurrence rate of 1.2%. Of these 5 failures, 2 were true recurrences/marginal misses, yielding a 5-year actuarial true recurrence/marginal miss rate of 0.5%. The 5-year actuarial cause-specific survival rate was 99% for APBI patients.

CONCLUSIONS

In selected patients with early-stage breast cancer, APBI with targeted interstitial brachytherapy offers 5-year results comparable with conventional breast-conserving therapy employing whole-breast radiation therapy. Minimal long-term toxicities were noted, most of which demonstrated continued resolution over time. Acceptable acute (7%) and delayed (4%) infection rates were observed. Fat necrosis was identified with increasing frequency with time, but the majority was asymptomatic. Cosmetic results are good to excellent (>90%). Continued follow-up by the surgeon will be required to determine the long-term efficacy of this alternative treatment approach.