Quantifying the reproducibility of heart position during treatment and corresponding delivered heart dose in voluntary deep inhalation breath hold for left breast cancer patients treated with external beam radiotherapy.

PURPOSE: Voluntary deep inhalation breath hold (VDIBH) reduces heart dose during left breast irradiation. We present results of the first study performed to quantify reproducibility of breath hold using bony anatomy, heart position, and heart dose for VDIBH patients at treatment table. METHODS AND MATERIALS: Data from 10 left breast cancer patients undergoing VDIBH whole-breast irradiation were analyzed. Two computed tomography (CT) scans, free breathing (FB) and VDIBH, were acquired to compare dose to critical structures. Pretreatment weekly kV orthogonal images and tangential ports were acquired. The displacement difference from spinal cord to sternum across the isocenter between coregistered planning Digitally Reconstructed Radiographs (DRRs) and kV imaging of bony thorax is a measure of breath hold reproducibility. The difference between bony coregistration and heart coregistration was the measured heart shift if the patient is aligned to bony anatomy. RESULTS: Percentage of dose reductions from FB to VDIBH: mean heart dose (48%, SD 19%, p = 0.002), mean LAD dose (43%, SD 19%, p = 0.008), and maximum left anterior descending (LAD) dose (60%, SD 22%, p = 0.008). Average breath hold reproducibility using bony anatomy across the isocenter along the anteroposterior (AP) plane from planning to treatment is 1 (range, 0-3; SD, 1) mm. Average heart shifts with respect to bony anatomy between different breath holds are 2 ± 3 mm inferior, 1 ± 2 mm right, and 1 ± 3 mm posterior. Percentage dose changes from planning to delivery: mean heart dose (7%, SD 6%); mean LAD dose, ((9%, SD 7%)S, and maximum LAD dose, (11%, SD 11%) SD 11%, p = 0.008). CONCLUSION: We observed excellent three-dimensional bony registration between planning and pretreatment imaging. Reduced delivered dose to heart and LAD is maintained throughout VDIBH treatment.

Primary nasopharyngeal interdigitating dendritic cell tumor presentation and response to radiation therapy.

We report the case of a primary nasopharyngeal interdigitating dendritic cell tumor (IDDCT). A 25-year old male presented with bilateral decreased hearing, double vision, and ataxia. Flexible nasopharyngoscopy reviewed a large mass obstructing and filling the entire nasopharynx. MRI and PET-CT confirmed the presence of the primary tumor and demonstrated bilateral cervical lymphadenopathy. Biopsy of the nasopharynx revealed a hematolymphoid neoplasm with dendritic cell differentiation, most consistent with an IDDCT. The lesion was unresectable. The patient was treated with definitive radiotherapy to 66 Gy to the primary tumor and 50 Gy to the bilateral cervical lymphatics using an IMRT technique. A complete response was achieved and the patient remains disease free at the primary site 23 months after completion of radiotherapy.

Clinical nodal staging of T1-2 tonsillar squamous cell carcinoma stratified by p16 status and implications for ipsilateral neck irradiation.

BACKGROUND AND PURPOSE: Previous studies have reported <5% incidence of contralateral nodal metastasis in patients with T1-2 tonsillar squamous cell carcinoma. We analyzed the nodal staging of T1-2 tonsillar squamous cell carcinoma stratified for p16 status, a marker of human papillomavirus positivity. MATERIALS AND METHODS: Clinical and radiographic nodal staging and p16 status of 41 T1-2 tonsillar squamous cell carcinoma patients who were treated between January 2002 and June 2009 were retrospectively analyzed. Patients with a history of prior head and neck cancer, synchronous cancers, base of tongue or soft palate invasion, or distant metastases at diagnosis were excluded. RESULTS: Of the 41 patients, 28 (68.2%) had p16+ tumors and 13 (31.7%) had p16- tumors. Seven patients (17.0%) presented with contralateral cervical nodal disease, all of whom had p16+ tumors. Furthermore, 25.0% of patients with p16+ tumors presented with contralateral cervical nodal disease compared with 0% of patients with p16- tumors. CONCLUSIONS: Patients with p16+ T1-2 tonsillar squamous cell carcinoma present with a higher incidence of contralateral nodal spread than those patients with p16- disease. This may have clinical implications when determining which patients are good candidates for ipsilateral cervical nodal irradiation.

Survey on human papillomavirus/p16 screening use in oropharyngeal carcinoma patients in the United States.

BACKGROUND: Patients with human papillomavirus (HPV)-positive oropharyngeal carcinoma (OC) have better prognosis than patients with HPV-negative OC. The objective of the current study was to assess how different practices across the United States treat patients with OC with respect to screening for HPV DNA or p16. METHODS: Five hundred forty-two randomly selected radiation oncologists were sent an 11-question survey by email regarding the use of HPV/p16 screening in OC. The questionnaire addressed demographics of the practice, intensity-modulated radiotherapy (IMRT) use, screening practices for HPV DNA or p16, which year this began, the use of HPV or p16 data to direct patient care, and future plans for its use if it had not already been instituted. RESULTS: One hundred ninety-two responses (39.6%) were received. Thirty-five percent of respondents (67 of 188) reported screening for HPV DNA routinely, whereas 4.8% of respondents (9 of 188) reported screening for p16. Of the physicians who did not use screening techniques, 37.2% (44 of 118 respondents) reported future plans to institute these screening techniques, 20% (9 of 45 respondents) stated plans to institute these techniques in the next 6 months, 55.5% (25 of 45 respondents) stated plans to institute these techniques within 6 months to 1 year, and 22.2% (10 of 45 respondents) stated plans to institute these techniques within 1 to 2 years. Academic physicians were more likely to use screening techniques (62.7%; P < .001) compared with private practitioners (31.4%). Only 12.4% of respondents reported using HPV or p16 data to direct care. CONCLUSIONS: Approximately 40.4% of radiation oncology practices that responded to a survey in the United States screened for HPV DNA or p16 in OC, whereas only 12.4% used it to further direct care. This number appears to be growing rapidly. Clinical trials to further elucidate how HPV or p16 status should direct care in OC are warranted.

Predicting residual neck disease in patients with oropharyngeal squamous cell carcinoma treated with radiation therapy: utility of p16 status.

OBJECTIVE: To identify factors that predict complete response of cervical nodal disease to radiation therapy (RT) in patients with oropharyngeal squamous cell carcinoma (OP-SCCA). DESIGN: Histologic analysis of prospectively collected specimens and retrospective medical chart review. SETTING: Tertiary referral center. SUBJECTS: Sixty-nine patients with OP-SCCA treated from January 1, 2002, through June 1, 2008. INTERVENTION: Definitive RT, with or without chemotherapy and with or without neck dissection (ND). MAIN OUTCOME MEASURE: Presence of a viable tumor in post-RT ND specimen. RESULTS: Tissue specimens from 69 patients with OP-SCCA treated primarily with RT, with or without chemotherapy, were evaluated. Of these, 47 (68.1%) were strongly and diffusely positive for p16 expression by immunohistochemical analysis, signifying human papillomavirus positivity. Patients with p16-positive and p16-negative tumors (hereinafter, p16+ and p16-, respectively) had similarly sized primary tumors on presentation, but p16+ primary tumors were associated with more advanced neck disease (nodal stages N2c-N3; 31.9% vs 4.5% for p16- tumors) and more contralateral nodes (27.7% vs 4.5% for p16- tumors). Forty-seven patients (59.0%) underwent planned posttreatment ND (a total of 55 NDs). The NDs performed for p16- tumors were significantly more likely to have viable tumor in the specimen (50.0% vs 18.0% for p16+ tumors; P = .02). In addition, p16+ necks with residual viable cancer were characterized by incomplete response on post-RT imaging, tobacco and alcohol use, and extracapsular spread on pretreatment imaging. CONCLUSIONS: In conjunction with other clinical parameters, p16 status can help predict the need for post-RT ND in patients with OP-SCCA. Although close observation may be warranted in selected patients with p16+ tumors, patients with p16- tumors are at much higher risk for residual neck disease, even when initial nodal disease is less advanced.

Calculation and prediction of the effect of respiratory motion on whole breast radiation therapy dose distributions.

The standard treatment technique used for whole-breast irradiation can result in undesirable dose distributions in the treatment site, leading to skin reaction/fibrosis and pulmonary and cardiac toxicities. Hence, the technique has evolved from conventional wedged technique (CWT) to segment intensity-modulated radiation therapy (SIMRT) and beamlet IMRT (IMRT). However, these newer techniques feature more highly modulated dose distributions that may be affected by respiration. The purpose of this work was to conduct a simple study of the clinical impact of respiratory motion on breast radiotherapy dose distributions for the three treatment planning techniques. The ultimate goal was to determine which patients would benefit most from the use of motion management. Eight patients with early-stage breast cancer underwent a free-breathing (FB) computed tomography (CT) simulation, with medial and lateral markers placed on the skin. Two additional CT scans were obtained at the end of inspiration (EI) and the end of expiration (EE). The FB-CT scan was used to develop treatment plans using each technique. Each plan was then applied to EI and EE-CT scans. Compared with the FB CT scan, the medial markers moved up to 1.8 cm in the anterior-superior direction at the end of inspiration (EI-scan), and on average 8 mm. The CWT and SIMRT techniques were not "sensitive" to respiratory motion, because the % clinical target volume (CTV) receiving 95% of the prescription dose (V(95%)) remained constant for both techniques. For patients that had large respiratory motion indicated by marker movement >0.6 cm, differences in coverage of the CTV at the V100% between FB and EI for beamlet IMRT plans were on the order of >10% and up to 18%. A linear model was developed to relate the dosimetric coverage difference introduced by respiration with the motion information. With this model, the dosimetric coverage difference introduced by respiratory motion could be evaluated during patient CT simulation. An appropriate treatment method can be chosen after the simulation.