Posted April 14, 2005 (published Nov-Dec 2004). Patients diagnosed with prostate cancer are commonly told to slow down and do their research before selecting any treatment. But can a patient wait too long? A study by radiation oncologists David Mansur and Jeff Michalski at Mallinckrodt Institute of Radiology, Siteman Cancer Center, Washington University Medical Center, St. Louis, MO suggests that for men with T2 stage prostate cancer, more than nine weeks is too long to wait around.
The team looked at medical records of 1083 patients with localized prostate cancer treated between 1970 and December 1999 with external irradiation alone. Median follow-up was 6 years (range, 4-24 years). For those treated after the PSA test was introduced in 1987 (687 patients) the researchers reviewed PSA levels before radiation therapy, and all patients seen in follow-up had prostate-specific antigen determinations.
Patient stage
Of the total number of patients, 344 patients had been classified as stage T1c, 496 with T2, and 243 with T3. The elapsed treatment time was divided into below or equal to 7, 7.1-9, or above 9 weeks. Local tumor control was determined by rectal examination and cause-specific survival or prostate-specific antigen failure according to American Society of Therapeutic Radiology and Oncology consensus criteria.
Dose level
Because of dose-escalation studies at the time these patients were treated, tumor dose levels ranged from 66-73.8 Gy, given in 1.8- to 2-Gy fractions.
Results
In patients with stage T1c, local failure ranged from 0% to 10% with doses below or equal to 72 Gy; elapsed treatment time had no impact. No pelvic failures were detected in 88 patients receiving doses above 72 Gy.
In patients with T2 who received less than or equal to 70 Gy, overall pelvic failure rate was 4% (12/306) in those with an elapsed treatment time of 9 weeks or less, in contrast to 27% (12/44) for those with an elapsed treatment time over 9 weeks.
At 10 years, patients with T2 tumors who had not received treatment until after elapse of more than 9 weeks had a higher actuarial pelvic failure rate (35%), in contrast to 5% to 18% with shorter treatment times.
For patients with T2 tumors who received 70-72 Gy, pelvic failure rate ranged from 0% to 32%, and there were no failures in 37 patients treated to higher doses.
In patients with PSA values whose tumors were stage T1c, the chemical failure rate was 41% (60/147) with a tumor dose below 70 Gy, compared with 17% (4/24) in those who received higher doses.
In patients with stage T2 disease who were treated with below 70 Gy, the chemical failure rate was 31%, and the rate was 12%-18% in those who received higher doses.
In stage T3, the clinical pelvic failure rate ranged from 25% to 32% in the three elapsed time groups, and the chemical failure rate ranged from 48% to 69%, and there was no significant correlation with elapsed time or total irradiation dose.
In patients with stage T1c disease, cause-specific survival without PSA recurrence (biochemical failure) at 10 years was 85%-90% in the three elapsed treatment time groups.
In patients with stage T2 disease, the corresponding values were 80% and 90% for elapsed treatment times below 9 weeks, in contrast to 65% for patients treated after more than 9 weeks.
In patients with stage T3 disease, cause-specific survival was about 60% in all elapsed treatment groups. There was no significant correlation of elapsed treatment time with urinary or rectal morbidity.
Conclusions
Patients treated with radiation therapy for stage T2 localized prostate carcinoma showed a greater incidence of pelvic and chemical failures and a lower cause-specific survival when elapsed treatment time was more than 9 weeks in comparison with the failure and survival rates occurring with shorter times. Higher doses of irradiation (above 72 Gy) eliminate the influence of prolongation of treatment time on outcome.
An earlier study from Fox Chase Cancer Center presented at ASTRO October 5, 2004 found that men who wait as long as three months after their prostate cancer diagnosis to receive radiation treatment do not fare worse than those who have treatment sooner.
The study was published in Cancer J. 2004 Nov-Dec;10(6):349-56:
Impact of elapsed treatment time on outcome of external-beam radiation therapy for localized carcinoma of the prostate.
Perez CA, Michalski J, Mansur D, Lockett MA.
Department of Radiation Oncology, Mallinckrodt Institute of Radiology, Siteman Cancer Center, Washington University Medical Center, St. Louis, Missouri.
Siteman Cancer Center is A National Cancer Institute Comprehensive Cancer Center in Saint Louis Missouri.
For treatment information contact the Urological Cancer Physician Team
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This article edited by J. Strax, Oct 6, 2004
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