Faculty Bibliography

PURPOSE/OBJECTIVE:To determine survival rates of patients with locally recurrent nasopharynx cancer (LRNPC) treated with modern therapeutic modalities. METHODS AND MATERIALS/METHODS:From July 1996 to March 2008, 29 patients were reirradiated for LRNPC. Thirteen patients received combined-modality treatment (CMT), consisting of external beam radiotherapy (EBRT) followed by intracavitary brachytherapy, whereas 16 received EBRT alone. The median age was 50 years, 59% were male, 38% were Asian, 69% had World Health Organization Class III histology, and 86% were treated for their first recurrence. Nine, 6, 8, and 6 patients had recurrent Stage I, II, III, and IV disease, respectively. Patients in the EBRT-alone group had more advanced disease. Median time to reirradiation was 3.9 years. In total, 93% underwent imaging with positron emission tomography and/or magnetic resonance imaging before reirradiation, 83% received intensity-modulated radiotherapy, and 93% received chemotherapy, which was platinum-based in 85% of cases. RESULTS:The median follow-up for all patients was 45 months and for surviving patients was 54 months. Five-year actuarial local control, event-free survival, and overall survival rates were 52%, 44%, and 60%, respectively. No difference was observed between patients treated with EBRT or CMT. Overall survival was superior in patients who achieved local control (p = 0.0003). The incidence of late Grade > or =3 events in patients re-treated with EBRT alone was significantly increased compared with those receiving CMT (73% vs. 8%; p = 0.005). CONCLUSIONS:In this modern reirradiation series of patients with LRNPC, favorable overall survival compared with historical series was achieved. Patients treated with CMT experienced significantly fewer severe late effects compared with those treated with EBRT.

PURPOSE/OBJECTIVE:To use radiation exposure rate measurements to determine patient-specific radiation safety instructions with the aim of reducing unnecessary precaution times and to evaluate potential doses to members of the public. METHODS AND MATERIALS/METHODS:Radiation exposure rate measurements were obtained from 1279 patients with Stage T1-2 prostate cancer who underwent transperineal (125)I or (103)Pd seed implantation from January 1995 through July 2008. An algorithm was developed from these measurements to determine the required precaution times to maintain public effective doses below 50% of the limits for specific exposure situations. RESULTS:The median air kerma rates at 30 cm from the anterior skin surface were 4.9 microGy/h (range: 0.1-31.5) for (125)I and 1.5 microGy/h (range: 0.02-14.9) for (103)Pd. The derived algorithms depended primarily on the half-life T(p), the measured exposure rate at 30 cm, and specific exposure situation factors. For the typical (103)Pd patient, no radiation safety precautions are required. For the typical (125)I patient, no precautions are required for coworkers, nonpregnant adults who do not sleep with the patient, or nonpregnant adults who sleep with the patient. Typical (125)I patients should only avoid sleeping in the "spoon" position (i.e., in contact) with pregnant adults and avoid holding a child for long periods of time in the lap for about 2 months. CONCLUSIONS:The large number of cases available for this study permitted the development of an algorithm to simply determine patient-specific radiation safety instructions. The resulting precaution times are significantly less restrictive than those generally prescribed currently.

PURPOSE/OBJECTIVE:To report the influence of posttreatment prostate-specific antigen (PSA) nadir response at 2 years after external beam radiotherapy (RT) on distant metastases (DM) and cause-specific mortality (CSM). METHODS AND MATERIALS/METHODS:Eight hundred forty-four patients with localized prostate cancer were treated with conformal RT. The median duration of follow-up was 9.1 years. A fixed landmark time point at 2 years was used to assess the influence of nadir PSA value as a time-dependent variable on long-term outcomes. RESULTS:Multivariate analysis demonstrated that nadir PSA <or=1.5 ng/mL at the landmark was an independent predictor of progression-free survival after adjusting for T stage, Gleason score, pre-RT PSA value, and RT dose (p = 0.03). The 5- and 10-year cumulative incidences of DM were 2.4% and 7.9%, respectively, in those with nadir PSA levels <or=1.5 ng/mL at the 2-year landmark, and were 10.3% and 17.5%, respectively, in patients with higher nadir values. Multivariate analysis showed that the higher nadir PSA value at the 2-year landmark (p = 0.002), higher Gleason scores (p < 0.001), and increasing T stage (p = 0.03) were predictors of DM after adjusting for pre-RT PSA values and RT dose. Multivariate analysis also showed that higher Gleason scores (p = 0.002), and higher nadir PSA values at the 2-year landmark (p = 0.03) were risk factors associated with CSM after adjusting for T stage and pre-RT PSA value. CONCLUSIONS:Nadir PSA values of <or=1.5 ng/mL at 2 years after RT for prostate cancer predict for long-term DM and CSM outcomes. Patients with higher absolute nadir levels at 2 years after treatment should be evaluated for the presence of nonresponding disease, and earlier salvage treatment interventions should be considered.