A dosimetric study of radionuclide therapy for bone marrow ablation

In a phase I clinical trial, six multiple myeloma patients, who were non-responsive to conventional therapy and were scheduled for bone marrow transplantation, received Holmium-166 ($\sp{166}$Ho) labeled to a bone seeking agent, DOTMP (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylene-phosphonic acid), for the purpose of bone marrow ablation. The specific aims of my research within this protocol were to evaluate the toxicity and efficacy of $\sp{166}$Ho DOTMP by quantifying the in vivo pharmacokinetics and radiation dosimetry, and by correlating these results to the biologic response observed. The reproducibility of pharmacokinetics from multiple injections of $\sp{166}$Ho DOTMP administered to these myeloma patients was demonstrated from both blood and whole body retention. The skeletal concentration of $\sp{166}$Ho DOTMP was heterogenous in all six patients: high in the ribs, pelvis, and lumbar vertebrae regions, and relatively low in the femurs, arms, and head.^ A novel technique was developed to calculate the radiation dose to the bone marrow in each skeletal ROI, and was applied to all six $\sp{166}$Ho DOTMP patients. Radiation dose estimates for the bone marrow calculated using the standard MIRD "S" factors were compared with the average values derived from the heterogenous distribution of activity in the skeleton (i.e., the regional technique). The results from the two techniques were significantly different; the average of the dose estimates from the regional technique were typically 30% greater. Furthermore, the regional technique provided a range of radiation doses for the entire marrow volume, while the MIRD "S" factors only provided a single value. Dose volume histogram analysis of data from the regional technique indicated a range of dose estimates that varied by a factor of 10 between the high dose and low dose regions. Finally, the observed clinical response of cells and abnormal proteins measured in bone marrow aspirates and peripheral blood samples were compared with radiation dose estimates for the bone marrow calculated from the standard and regional technique. The results showed the regional technique values correlated more closely to several clinical response parameters. (Abstract shortened by UMI.) ^

A case-control study of bilateral compared with unilateral breast cancer

Approximately 10 to 15% of breast cancer patients develop a primary cancer in the contralateral breast. This study examined differences between women with unilateral compared with bilateral primary breast cancer. It focused on hormonal factors and family history, and evaluated the prevalences of invasive lobular histology and the replication error phenotype in the tumors. ^ Cases (n = 82) were patients at M.D. Anderson Cancer Center (MDACC) in Houston, Texas diagnosed with primary breast cancer in each breast between 1985 and 1994 inclusive. Controls (n = 82) were MDACC patients with primary cancer in a single breast diagnosed during the same interval, individually matched to cases. Data were obtained by in-person and/or telephone interview with the patient and/or proxy. Replication error phenotype was determined from archival tissue. ^ Diagnosis of breast, but not ovarian, cancer in a female first-degree relative (FFDR) was a strong risk factor for bilateral cancers. Cases had a significantly 3-fold higher excess of familial breast cancer than did controls (cases: O/E = 2.65, 95% CI = 1.85–3.69; controls: 0.86, 0.46–1.47; homogeneity: p = 0.00). Risk did not vary with menopausal status of the patient, but was greatest if a relative was diagnosed before age 45 (O/E = 38.9; 95% CI = 21.7–64.1). By implication, young first-degree relatives of patients with bilateral breast cancer are at very high risk of breast cancer themselves. Cases also had significantly fewer siblings than did controls. ^ Earlier menarche, and parity in the absence of lactation, were associated with bilateral cancers; age at menopause and parity with lactation were not. A history of alcohol consumption, particularly if heavy, carried a 3.4-fold risk (p = 0.03). The data suggested a slightly different pattern in risk factors according to menopausal status and interval between cancers. ^ Replication error phenotype was available for 59 probands. It was associated with bilateral cancers (particularly if diagnosed within one year of each other), increased age (p = 0.02) and negative nodal status. Invasive lobular histology was associated with bilateral disease but numbers were small. ^ These data suggest bilateral breast cancer arises in the context of a combination of familial and hormonal factors, and alcohol consumption. The relative importance of each factor may vary by age of the patient. ^

Cost-effectiveness analysis of stereotactic body radiotherapy and radiofrequency ablation for medically inoperable liver metastases from colorectal cancer

This report describes the development of a Markov model for comparing percutaneous radiofrequency ablation (RFA) and stereotactic body radiation therapy (SBRT) in terms of their cost-utility in treating isolated liver metastases from colorectal cancer. The model is based on data from multiple retrospective and prospective studies, available data on different utility states associated with treatment and complications, as well as publicly available Medicare costs. The purpose of this report is to establish a well-justified model for clinical management decisions. In comparison with SBRT, RFA is the most cost-effective treatment for this patient population. From the societal perspective, SBRT may be an acceptable alternative with an ICER of $28,673/QALY. ^