BACKGROUND: Although the standard therapy for locally advanced hypopharyngeal cancer remains surgery and postoperative radiotherapy (RT), alternative treatment approaches include induction chemotherapy and RT. The purpose of this retrospective study was to compare the long-term outcome of these treatments performed in a single institution. METHODS: Twenty-six patients with advanced, resectable, squamous cell carcinoma of the hypopharynx were treated with induction chemotherapy and definitive RT (group I), reserving laryngectomy for salvage. The induction phase of therapy consisted of 2-3 cycles of cisplatin-based chemotherapy followed by conventional fractionated RT to doses of 66-70 Gy. The outcomes of this group of patients were compared with the outcomes of 30 patients with hypopharyngeal cancer who were treated at our institution with surgery and postoperative RT (group II). The median follow-up times of the surviving patients in groups I and II were 5 and 9 years, respectively. RESULTS: The local recurrence-free survival at 5 years from the completion of therapy for group I was 50%, compared with 69% for group II (p = .41). Among patients with T3-T4 primary tumors, the 5-year local control rates were 58% and 59% for groups I and II, respectively (p = .78). The likelihood of larynx preservation, free of local disease at 5 years for group I, was 52%. The 5-year neck recurrence-free survival for groups I and II were 47% and 69%, respectively (p = .66). Among patients with N2-N3 stage disease, the 5-year incidence of neck failure for groups I and II were 73% and 68%, respectively (p = .74). The 5-year distant metastases-free survival for groups I and II were 67% and 57%, respectively (p = .19). The 5-year disease-free survival rates for groups I and II were 30% and 42%, respectively (p = .9). The 5-year overall survival rates for groups I and II were 15% and 22%, respectively (p = .65). CONCLUSIONS: Nonsurgical therapy for advanced stage hypopharyngeal cancer provides survivorship comparable with that achieved with standard approaches of surgery and postoperative RT. However, despite the therapy, the outcome is poor. Future studies will need to explore new treatment strategies in an effort to improve upon the outcome for this group of patients.

Adult↗

PubMedDate not supplied

Applications of brachytherapy in head and neck cancer.

Brachytherapy offers the radiation oncologist the opportunity to deliver high doses of radiation to the tumor, with minimal doses to the surrounding normal tissue. This combination enhances the therapeutic ratio. It allows for enhanced tumor control, with minimal toxicity. When utilized, it often allows for tumor control without the need for resection. This is especially important in the head and neck. Resection of organs such as the lip, oral tongue, base-of-tongue, and other sites can cause significant functional and cosmetic morbidity. The ability to save these structures, using radiation therapy instead of surgery, can provide excellent tumor control and optimal quality-of-life outcome. In situations of recurrent disease, especially when prior radiation has been given, brachytherapy is often the only way to re-irradiate certain areas. This can be done alone, or in combination with surgery. Therefore, brachytherapy becomes an important component of the treatment of recurrent disease. This broad overview of the use of brachytherapy in head and neck cancer will include applications in the primary as well as the recurrent disease setting.

Brachytherapy↗

PubMedDate not supplied

Results and complications of surgery combined with intra-operative radiation therapy for the treatment of locally advanced or recurrent cancers in the pelvis.

Intra-operative radiation therapy (IORT) can benefit patients with pelvic tumors by delivering a high dose of radiation with precise delineation of tumor bed and maximal protection of surrounding normal tissues. The IORT experience has been particularly promising for locally advanced primary or recurrent rectal cancers in which a gross total resection is achieved. However, its potential benefit must be weighed against added toxicity. The main dose-limiting toxicity of pelvic IORT is peripheral neuropathy and ureteral stenosis. We will review the techniques for optimal IORT delivery, the results of the major studies investigating IORT treatment of rectal cancer, and the pelvic complications associated with combining surgery and IORT. A team of surgeons and radiation oncologists providing close multidisciplinary coordination is essential to integrate IORT with combined modality regimens in a safe and effective manner.

Animals↗

PubMedDate not supplied

Postoperative radiotherapy for oral cavity cancers: impact of anatomic subsite on treatment outcome.

We have retrospectively reviewed the treatment results of postoperative radiotherapy (RT) for advanced oral cavity cancers. The purpose of this study was to determine the impact of anatomic subsite on the results of treatment. Between 1975 and 1985, 51 patients with squamous cell carcinoma of the oral tongue (OT = 29 patients) and floor of mouth (FOM = 22 patients) were treated with combined surgery plus RT. All had an indication(s) for RT including advanced primary disease (T3 or T4) (29 patients), close or positive margins (34 patients), and multiple positive neck nodes and/or extracapsular extension (41 patients). With a median follow-up of 6 years, the 5-year actuarial local control rate was 74% and the rate of distant metastasis (DM) was 34%. Despite the similar T stage, margin status and median RT dose, the 5-year actuarial local failure rate was 38% for OT vs. 11% for FOM (p = 0.03). Furthermore, the median survival after recurrence was 9 months for OT and 40 months for FOM (p = 0.02). At 5 years the determinate survival for both sites was (55%), and the likelihood of developing a second malignancy was 31%. The likelihood of developing DM was 50% for FOM (N0-N1 = 3 of 12, N2-N3 = 8 of 10) and 21% for OT (N0-N1 = 4 of 21, N2-N3 = 1 of 8). This study highlights significant differences between FOM and OT cancers in response to combined surgery and RT. Future strategies should be directed at the enhancement of local control for OT and better systemic therapy for those with advanced N-stage FOM.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoma, Squamous Cell↗

PubMedDate not supplied

Esthesioneuroblastoma: is there a role for elective neck treatment?

A retrospective review of the Memorial Sloan Kettering Cancer Center experience (MSKCC) with esthesioneuroblastoma was performed. From 1975 to 1985 14 cases were identified. Overall 5- and 10-year survival was 86% and 70%, respectively. Four local failures were observed and 4 neck failures were observed. A review of the literature since 1966 revealed an unexpectedly high incidence of neck failure, and of the 21 of 110 patients with neck failures that were identified through the literature, there were 6 subsequent deaths.

Adult↗

PubMedDate not supplied

Treatment planning dosimetric parameters for a (90)Y coil source used in intravascular brachytherapy.

BACKGROUND: (90)Y coil sources have been used in animal and clinical trials for treatment of restenosis in intravascular brachytherapy (IVBT). This study aims to determine the American Association of Physicists in Medicine (AAPM) Task Group-60 (TG-60) dosimetric quantities in regions surrounding the balloon wall for use in treatment planning computer systems. METHODS: The Monte Carlo method was used to determine the dose distribution, using MCNP4B2 code. The coil source was modeled by a hollow cylinder of 2.9 cm length centered in a balloon (2.5 mm diameter) filled with carbon dioxide (CO(2)) at 5 atm. Scoring voxels consisted of contiguous annular disk shells with 0.1 mm spacing in the radial direction and 0.2 mm spacing in the longitudinal direction. The scoring region ranges from the center of the source to 1.0 cm in the longitudinal direction, and from 0.13 to 1 cm in the radial direction. In the plane containing the source axis, the Monte Carlo-generated doses in rectilinear coordinates are converted to polar coordinates. RESULTS: The dose rate of the source is provided in both Cartesian and polar coordinates. The dose rate constant [D(r(0),theta(0))], anisotropy function [F(r,theta)], and radial dose function [g(r)] were generated from these values and listed in tabular format. At shallow angles and longer distances from the source center, large values of the anisotropy function resulted, deviating two orders of magnitude from unity. CONCLUSIONS The doses given to the intima, media, and adventitia are very crucial quantities in IVBT. The calculated TG-60 dosimetric quantities, used commonly in conventional brachytherapy applications, provide a means for the user to determine the three-dimensional dose surrounding the balloon catheter. These parameters can be used in future treatment planning system for IVBT. We also discuss the need to develop a new formalism specific to longer sources used in IVBT.

Angioplasty, Balloon, Coronary↗

PubMedDate not supplied

A new treatment planning formalism for catheter-based beta sources used in intravascular brachytherapy.

Intravascular brachytherapy (IVBT) is an emerging modality for the treatment of atherosclerotic lesions in the artery. As part of the refinement in this rapidly evolving modality of treatment, the current simplistic dosimetry approach based on a fixed-point prescription must be challenged by future rigorous dosimetry method employing image-based three-dimensional (3D) treatment planning. The goals of 3D IVBT treatment planning calculations include (1) achieving high accuracy in a slim cylindrical region of interest, (2) accounting for the edge effect around the source ends, and (3) supporting multiple dwell positions. The formalism recommended by Task Group 60 (TG-60) of the American Association of Physicists in Medicine (AAPM) is applicable for gamma sources, as well as short beta sources with lengths less than twice the beta particle range. However, for the elongated beta sources and/or seed trains with lengths greater than twice the beta range, a new formalism is required to handle their distinctly different dose characteristics. Specifically, these characteristics consist of (a) flat isodose curves in the central region, (b) steep dose gradient at the source ends, and (c) exponential dose fall-off in the radial direction. In this paper, we present a novel formalism that evolved from TG-60 in maintaining the dose rate as a product of four key quantities. We propose to employ cylindrical coordinates (R, Z, phi), which are more natural and suitable to the slim cylindrical shape of the volume of interest, as opposed to the spherical coordinate system (r, theta, phi) used in the TG-60 formalism. The four quantities used in this formalism include (1) the distribution factor, H(R, Z), (2) the modulation function, M(R, Z), (3) the transverse dose function, h(R), and (4) the reference dose rate at 2 mm along the perpendicular bisector, D(R0=2 mm, Z0=0). The first three are counterparts of the geometry factor, the anisotropy function and the radial dose function in the TG-60 formalism, respectively. The reference dose rate is identical to that recommended by TG-60. The distribution factor is intended to resemble the dose profile due to the spatial distribution of activity in the elongated beta source, and it is a modified Fermi-Dirac function in mathematical form. The utility of this formalism also includes the slow-varying nature of the modulation function, allowing for more accurate treatment planning calculations based on interpolation. The transverse dose function describes the exponential fall-off of the dose in the radial direction, and an exponential or a polynomial can fit it. Simultaneously, the decoupling nature of these dose-related quantities facilitates image-based 3D treatment planning calculations for long beta sources used in IVBT. The new formalism also supports the dosimetry involving multiple dwell positions required for lesions longer than the source length. An example of the utilization of this formalism is illustrated for a 90Y coil source in a carbon dioxide-filled balloon. The pertinent dosimetric parameters were generated and tabulated for future use.

Beta Particles↗

PubMedDate not supplied

Ytterbium-169: a promising new radionuclide for intravascular brachytherapy.

PURPOSE: To explore the feasibility of 169Yb (gamma, 93 keV) as a new radionuclide for intravascular brachytherapy (IVBT) in terms of dose distribution, penetration power, and radiation safety features as compared with 125I and 192Ir. METHODS: The dose distributions for catheter-based sources, 169Yb, 125I, and 192Ir, in homogeneous water and in the presence of calcium and a steel stent have been determined and compared using the Monte Carlo method (MCNP4B2 code). The dose rates of the sources were evaluated from 0.02 to 100 cm. RESULTS: In the short distance range (0.02<r<1.0 cm), the dose distributions in homogeneous water are very similar for the three radionuclides when the dose rates are normalized at 2 mm. Between 1 and 20 cm, the relative dose rates fall off similarly for 169Yb and 192Ir, whereas for 125I, it decreases much more rapidly. At a distance further away (r approximately 100 cm), the dose rate of 169Yb is about 10 times lower than that of 192Ir, indicating the cathlab radiation shielding requirement for 169Yb is substantially reduced as compared with 192Ir. Calcified plaques and stents cause a drastic dose reduction in the arterial wall for 125I, but have no effect for 192Ir gamma-rays. Only slight dose reductions were detected for 169Yb beyond a layer of 1.0-mm calcium (2-3%), and behind a steel stent strut (5%). CONCLUSION: 169Yb is a promising new radionuclide for IVBT. It has a much better penetrating power through calcified plaques and stents compared with the low-energy source 125I. It also provides easier radiation protection measures for cardiac cathlab personnel than the high-energy source 192Ir, while preserving a favorable dose distribution in tissues surrounding an arterial vessel.

Brachytherapy↗

PubMedDate not supplied

Effect of stent on radiation dosimetry in an in-stent restenosis model.

PURPOSE: Intravascular brachytherapy is the leading modality being evaluated for treatment of in-stent restenosis. Stent struts may have an effect on the dose distributions of various radiation sources. We evaluated dosimetry in a stented coronary artery model using a variety of beta and gamma sources and stent materials. METHODS: We determined the dose distributions with and without stent in the in-stent restenosis model. Three beta-particle emitting radionuclides, 90Y (2.3 MeV), 144Pr (3.0 MeV), and 106Rh (3.5 MeV), and two gamma-ray emitters, 192Ir (380 keV) and 125I (30 keV), were studied. Stent materials included stainless steel, nitinol, and tantalum. Monte Carlo dose calculations were performed in a stent model of multiple stent struts placed at 1.5 mm from the source. Isodose curves were generated and the ratios of dose rates with and without stent, the stent factors, were evaluated. A stent factor of greater or less than unity represents dose enhancement or reduction in the presence of a stent. RESULTS: For the three beta radionuclides, dose reduction was found on the adventitial side of the stent strut and dose enhancement was noted on the luminal side. On the luminal side, the maximum dose enhancement ranges from 7% to 29%, and the dose reduction on the adventitial side ranges from 13% to 43%. Both the reduction and enhancement effects were most pronounced for the high atomic number material, tantalum. For a given stent material, the dose reduction and enhancement are similar for the three beta radionuclides. For the gamma sources, the stent had no effect for the high-energy 192Ir, but for the low-energy 125I, drastic dose reduction on the adventitial side was observed (up to 86% for tantalum stent), and about 10% dose enhancement on the luminal side was also noted. The dose reduction with 125I was more pronounced than that seen with the beta sources. CONCLUSIONS: The presence of stent struts significantly affects dose distributions of 90Y, 106Rh, 144Pr, and 125I. The maximum dose reduction can be as much as 86%. 192Ir was unaffected. These factors need to be considered in choosing radionuclides and dose prescriptions in treating in-stent restenosis.

Brachytherapy↗

PubMedDate not supplied

Clinical comparison of the anticalculus efficacy of three commercially available dentifrices.

A three-month, double-blind, parallel and unsupervised clinical study was conducted to compare the effects on supragingival calculus formation of the following four dentifrices: 1) A placebo dentifrice containing 0.243% sodium fluoride in a silica base. 2) A commercially available anticalculus dentifrice containing 5.0% soluble pyrophosphate in a 0.243% sodium fluoride silica base. 3) A commercially available anticalculus dentifrice containing 1.3% soluble pyrophosphate and 1.5% of a Gantrez copolymer in a 0.243% sodium fluoride silica base. 4) A commercially available anticalculus dentifrice containing 3.3% soluble pyrophosphate and 1.0% of a Gantrez copolymer in a 0.243% sodium fluoride silica base. The three-month results indicated that the three commercially available anticalculus dentifrices provided statistically significant reductions (at the 99% level of confidence) in supragingival calculus formation of 43.87%, 46.60%, and 51.32% respectively, as compared to the placebo dentifrice. There was no statistically significant difference among the three commercially available anticalculus dentifrices.

Adult↗