Biomedical subjects

David A Pistenmaa

Publications and source records attributed to David A Pistenmaa.

3 recordsLinked to original sources

PubMed2005

Robotically guided radiosurgery for children.

BACKGROUND: A robotically guided linear accelerator has recently been developed which provides frameless radiosurgery with high precision. Potential advantages for the pediatric population include the avoidance of the cognitive decline associated with whole brain radiotherapy, the ability to treat young children with thin skulls unsuitable for frame-based methods, and the possible avoidance of general anesthesia. We report our experience with this system (the "Cyberknife") in the treatment of 21 children. PROCEDURES: Cyberknife radiosurgery was performed on 38 occasions for 21 patients, age ranging from 8 months to 16 years (7.0 +/- 5.1 years), with tumors considered unresectable. Three had pilocytic astrocytomas, two had anaplastic astrocytomas, three had ependymomas (two anaplastic), four had medulloblastomas, three had atypical teratoid/rhabdoid tumors, three had craniopharyngiomas, and three had other pathologies. The mean target volume was 10.7 +/- 20 cm(3), mean marginal dose was 18.8 +/- 8.1 Gy, and mean follow-up is 18 +/- 11 months. Twenty-seven (71%) of the treatments were single-shot and eight (38%) patients did not require general anesthesia. RESULTS: Local control was achieved in the patients with pilocytic and anaplastic astrocytoma, three of the patients with medulloblastoma, and the three with craniopharyngioma, but not for those with ependymoma. Two of the patients with rhabdoid tumors are alive 16 and 35 months after this diagnosis. There have been no procedure related deaths or complications. CONCLUSION: Cyberknife radiosurgery can be used to achieve local control for some children with CNS tumors without the need for rigid head fixation.

Adolescent↗

PubMed2004

Salvage radiotherapy for recurrent prostate cancer after radical prostatectomy.

CONTEXT: Salvage radiotherapy may potentially cure patients with disease recurrence after radical prostatectomy, but previous evidence has suggested that it is ineffective in patients at the highest risk of metastatic disease progression. OBJECTIVE: To delineate patients who may benefit from salvage radiotherapy for prostate cancer recurrence by identifying variables associated with a durable response. DESIGN, SETTING, AND PATIENTS: Retrospective review of a cohort of 501 patients at 5 US academic tertiary referral centers who received salvage radiotherapy between June 1987 and November 2002 for detectable and increasing prostate-specific antigen (PSA) levels after radical prostatectomy. MAIN OUTCOME MEASURE: Disease progression after salvage radiotherapy, defined as a serum PSA value > or =0.1 ng/mL above the postradiotherapy PSA nadir confirmed by a second PSA measurement that was higher than the first by any amount, by a continued increase in PSA level after treatment, or by the initiation of androgen deprivation therapy after treatment. RESULTS: Over a median follow-up of 45 months, 250 patients (50%) experienced disease progression after treatment, 49 (10%) developed distant metastases, 20 (4%) died from prostate cancer, and 21 (4%) died from other or unknown causes. The 4-year progression-free probability (PFP) was 45% (95% confidence interval [CI], 40%-50%). By multivariable analysis, predictors of progression were Gleason score of 8 to 10 (hazard ratio [HR], 2.6; 95% CI, 1.7-4.1; P<.001), preradiotherapy PSA level greater than 2.0 ng/mL (HR, 2.3; 95% CI, 1.7-3.2; P<.001), negative surgical margins (HR, 1.9; 95% CI, 1.4-2.5; P<.001), PSA doubling time (PSADT) of 10 months or less (HR, 1.7; 95% CI, 1.2-2.2; P =.001), and seminal vesicle invasion (HR, 1.4; 95% CI, 1.1-1.9; P =.02). Patients with no adverse features had a 4-year PFP of 77% (95% CI, 64%-91%). When treatment was given for early recurrence (PSA level < or =2.0 ng/mL), patients with Gleason scores of 4 to 7 and a rapid PSADT had a 4-year PFP of 64% (95% CI, 51%-76%) and of 22% (95% CI, 6%-38%) when the surgical margins were positive and negative, respectively. Patients with Gleason scores of 8 to 10, positive margins, and receiving early salvage radiotherapy had a 4-year PFP of 81% (95% CI, 57%-100%) when the PSADT was longer than 10 months and of 37% (95% CI, 16%-58%) when the PSADT was 10 months or less. CONCLUSIONS: Gleason score, preradiotherapy PSA level, surgical margins, PSADT, and seminal vesicle invasion are prognostic variables for a durable response to salvage radiotherapy. Selected patients with high-grade disease and/or a rapid PSADT who were previously thought to be destined to develop progressive metastatic disease may achieve a durable response to salvage radiotherapy.

Adult↗

PubMed2003

Salvage radiotherapy for biochemical failure of radical prostatectomy: a single-institution experience.

OBJECTIVES: To review the efficacy of salvage radiotherapy (RT), to treat elevated prostate-specific antigen (PSA) levels for presumed local recurrence of prostatic adenocarcinoma after retropubic prostatectomy, and identify the factors that may predict for successful treatment. METHODS: Fifty-one patients with hormonally naive pT2-3N0-1M0 prostate cancer were treated with RT for locally persistent or recurrent disease. The patients received a median dose of 65.7 Gy (range 61.2 to 72.3) to the prostate bed. Successfully treated patients had undetectable PSA levels; the endpoint of the study was biochemical failure. RESULTS: The median follow-up was 3.8 years; 42 of 51 patients had at least 2 years of follow-up. Twenty-three patients (45%) were biochemically free of disease. The estimated biochemically free of disease rate at 3 and 5 years was 56% and 16%, respectively. Whether the patients were treated for persistently elevated PSA levels or for rising PSA levels from undetectable levels after retropubic prostatectomy, their PSA values were equally likely to drop to undetectable levels (65%). Univariate analysis demonstrated two factors that significantly predicted for successful salvage treatment: the absence of seminal vesicle invasion and the absence of lymphovascular invasion. A pretreatment PSA level less than 0.425 ng/mL trended toward statistical significance (P = 0.059). Only seminal vesicle invasion maintained significance on multivariate analysis. The RT was well tolerated, and the gastrointestinal and genitourinary toxicity was largely Radiation Therapy Oncology Group grade 1. CONCLUSIONS: Salvage RT is moderately effective in treating patients with locally persistent or recurrent prostate adenocarcinoma. Seminal vesicle invasion and lymphovascular invasion predicted for unsuccessful treatment.

Adenocarcinoma↗