M. Spierer

Change in Seroma Volume During Whole-Breast Radiation Therapy

PURPOSE After breast-conserving surgery, a seroma often forms in the surgical cavity. If not drained, it may affect the volume of tumor bed requiring a boost after whole-breast radiation therapy (WBRT). Our objective was to evaluate the change in seroma volume that occurs during WBRT, before boost planning. METHODS AND MATERIALS A retrospective review was performed of women receiving breast-conserving therapy with evidence of seroma at the time of WBRT planning. Computed tomography (CT) simulation was performed before WBRT and before the tumor bed boost. All patients received either a hypofractionated (42.4 Gy/16 fraction + 9.6 Gy/4 fraction boost) or standard fractionated (50.4 Gy/28 fraction + 10 Gy/5 fraction boost) regimen. Seroma volumes were contoured and compared on CT at the time of WBRT simulation and tumor bed boost planning. RESULTS Twenty-four patients with evidence of seroma were identified and all patients received WBRT without drainage of the seroma. Mean seroma volume before WBRT and at boost planning were significantly different at 65.7 cm(3) (SD, 50.5 cm(3)) and 35.6 cm(3) (SD, 24.8 cm(3)), respectively (p < 0.001). Mean and median reduction in seroma volume during radiation were 39.6% (SD, 23.8%) and 46.2% (range, 10.7-76.7%), respectively. Fractionation schedule was not correlated with change in seroma volume. Length of time from surgery to start of radiation therapy showed an inverse correlation with change in seroma volume (Pearson correlation r = -0.53, p < 0.01). CONCLUSIONS The volume of seroma changes significantly during WBRT. Consequently, the accuracy of breast boost planning is likely affected, as is the volume of normal breast tissue irradiated. CT-based boost planning before boost irradiation is suggested to ensure appropriate coverage.

Long‐term outcomes in extremity soft tissue sarcoma after a pathologically negative re‐resection and without radiotherapy

The purpose was to define the rate of local recurrence (LR) and identify prognostic factors for LR in patients with extremity soft‐tissue sarcoma (STS) treated with limb‐sparing surgery and a pathologically negative re‐resection specimen without radiotherapy (RT).

Hypofractionated whole-breast radiation therapy: does breast size matter?

PURPOSE To evaluate the effects of breast size on dose-volume histogram parameters and clinical toxicity in whole-breast hypofractionated radiation therapy using intensity modulated radiation therapy (IMRT). MATERIALS AND METHODS In this retrospective study, all patients undergoing breast-conserving therapy between 2005 and 2009 were screened, and qualifying consecutive patients were included in 1 of 2 cohorts: large-breasted patients (chest wall separation>25 cm or planning target volume [PTV]>1500 cm3) (n=97) and small-breasted patients (chest wall separation<25 cm and PTV<1500 cm3) (n=32). All patients were treated prone or supine with hypofractionated IMRT to the whole breast (42.4 Gy in 16 fractions) followed by a boost dose (9.6 Gy in 4 fractions). Dosimetric and clinical toxicity data were collected and analyzed using the R statistical package (version 2.12). RESULTS The mean PTV V95 (percentage of volume receiving>=95% of prescribed dose) was 90.18% and the mean V105 percentage of volume receiving>=105% of prescribed dose was 3.55% with no dose greater than 107%. PTV dose was independent of breast size, whereas heart dose and maximum point dose to skin correlated with increasing breast size. Lung dose was markedly decreased in prone compared with supine treatments. Radiation Therapy Oncology Group grade 0, 1, and 2 skin toxicities were noted acutely in 6%, 69%, and 25% of patients, respectively, and at later follow-up (>3 months) in 43%, 57%, and 0% of patients, respectively. Large breast size contributed to increased acute grade 2 toxicity (28% vs 12%, P=.008). CONCLUSIONS Adequate PTV coverage with acceptable hot spots and excellent sparing of organs at risk was achieved by use of IMRT regardless of treatment position and breast size. Although increasing breast size leads to increased heart dose and maximum skin dose, heart dose remained within our institutional constraints and the incidence of overall skin toxicity was comparable to that reported in the literature. Taken together, these data suggest that hypofractionated radiation therapy using IMRT is a viable and appropriate therapeutic modality in large-breasted patients.

ICRU reference dose in an era of intensity-modulated radiation therapy clinical trials: correlation with planning target volume mean dose and suitability for intensity-modulated radiation therapy dose prescription.

BACKGROUND AND PURPOSE IMRT clinical trials lack dose prescription and specification standards similar to ICRU standards for two- and three-dimensional external beam planning. In this study, we analyzed dose distributions for patients whose treatment plans incorporated IMRT, and compared the dose determined at the ICRU reference point to the PTV doses determined from dose-volume histograms. Additionally, we evaluated if ICRU reference type single-point dose prescriptions are suitable for IMRT dose prescriptions. MATERIALS AND METHODS For this study, IMRT plans of 117 patients treated at our institution were randomly selected and analyzed. The treatment plans were clinically applied to the following disease sites: abdominal (11), anal (10), brain (11), gynecological (15), head and neck (25), lung (15), male pelvis (10) and prostate (20). The ICRU reference point was located in each treatment plan following ICRU Report 50 guidelines. The reference point was placed in the central part of the PTV and at or near the isocenter. In each case, the dose was calculated and recorded to this point. For each patient--volume and dose (PTV, PTV mean, median and modal) information was extracted from the planned dose-volume histogram. RESULTS The ICRU reference dose vs PTV mean dose relationship in IMRT exhibited a weak positive association (Pearson correlation coefficient 0.63). In approximately 65% of the cases studied, dose at the ICRU reference point was greater than the corresponding PTV mean dose. The dose difference between ICRU reference and PTV mean doses was 2% in approximately 79% of the cases studied (average 1.21% (+/-1.55), range -4% to +4%). Paired t-test analyses showed that the ICRU reference doses and PTV median doses were statistically similar (p=0.42). The magnitude of PTV did not influence the difference between ICRU reference and PTV mean doses. CONCLUSIONS The general relationship between ICRU reference and PTV mean doses in IMRT is similar to that in 3D CRT distributions. Point doses in IMRT are influenced by the degree of intensity modulation as well as calculation grid size utilized. Although the ICRU reference point type prescriptions conceptually may be extended for IMRT dose prescriptions and used as a representative of tumor dose, new universally acceptable dose prescription and specification standards for IMRT based on RTOG IMRT prescription model incorporating dose-volume specification would likely lead to greater consistency among treatment centers.

Clinical and molecular exploration of the impact of radiation therapy on Marfan syndrome patients

Marfan syndrome (MFS) is a heritable disorder of the connective tissue and has been linked to mutations in the fibrillin-1 (FBN) gene. Radiation-induced fibrosis has been considered a risk for radiation-induced toxicities in treating cancers in this patient population. FBN is an inhibitor of transforming growth factor beta (TGF-β) expression and its mutation is thought to result in TGF-β upregulation.1 MFS clinically presents in a conglomeration of symptoms that affect wound healing and have modulatory effects on TGF-β. Because abnormal TGF-β expression has previously been linked to radiation-induced fibrosis, the expectation is that these patients will experience higher levels of fibrosis or fibrotic sequelae. In this study, we report the clinical course of a MFS patient who is treated with breast conservation radiation therapy (RT) for ductal carcinoma in situ (DCIS) status post lumpectomy. With a reported incidence of 1 case per 10,000 people, MFS is typically characterized by tall stature, arachnodactyly, pectus, scoliosis and lordosis, nocturnal enuresis, joint laxity, mitral or aortic valve prolapse, and ectopia lentis (lens dislocation).2 Aortic dissection, rupture or cardiac failure, is the cause of death in 90% of patients.2

Primary Central Nervous System Lymphoma

Primary central nervous system lymphoma (PCNSL) is a rare malignancy that accounts for 2.5% of all brain tumors. This entity can involve the eyes and the entire central nervous system (CNS). PCNSL presents with focal neurological deficits, neuropsychiatric symptoms, and increased intracranial pressure. Systemic symptoms are uncommon. The initial diagnosis is based on brain magnetic resonance imaging (MRI) findings, and histological confirmation is needed via either vitreous biopsy, cerebral spinal fluid sampling (CSF), or a stereotactic brain biopsy. Prognosis is highly dependent on patient age (>50 years) and performance status. Overall survival will vary and can be greater than 5 years for young patients with excellent performance status and less than 1 year for the elderly patients, with poor performance status. PCNSL is a very radiation-sensitive malignancy; however, long-term survivors are rare in those who receive radiation alone. Great strides have been made with high-dose methotrexate (MTX)-based chemotherapy, with current median survival greater than 40 months. Combination of MTX-based chemotherapy and whole-brain radiation therapy (WBRT) can yield devastating neurotoxicity, with some series reporting greater than 80% incidence in patients older than 60 years of age. The current data for treatment are limited, with only two fully accrued randomized trial, and many heterogeneous phase II and retrospective series. One recently presented abstract of a randomized trial of high dose MTX plus or minus WBRT demonstrated a benefit in progression free survival for WBRT but no overall survival benefit. Current treatment trends include integration of newer chemotherapeutic/targeted agents with MTX-based chemotherapy and response-based indications for radiation therapy with possible dose de-escalation.

Placement of MammoSite® Brachytherapy Catheter under Computed-Tomography Scan Guidance

Placement of the MammoSite® breast brachytherapy catheter is most commonly performed either intraoperatively or under ultrasound-guided technique. Below, we present a case report of an alternate approach utilizing CT-scan guidance. This is the first reported case of a balloon brachytherapy catheter placement with this technique.