Impact of Elapsed Treatment Time on Outcome of External-Beam Radiation Therapy for Localized Carcinoma of the Prostate

PURPOSE

The purpose of this study was to evaluate the impact of elapsed treatment time in external-beam radiation therapy for localized prostate carcinoma.

MATERIALS AND METHODS

The medical records of 1083 patients with localized prostate carcinoma treated between 1970 and December 1999 with external irradiation alone were reviewed. Median follow-up was 6 years (range, 4-24 years). Since 1987, prostate-specific antigen levels were obtained in 687 patients before the initiation of radiation therapy, and all patients seen in follow-up had prostate-specific antigen determinations. There were 344 patients with T1c, 496 with T2, and 243 with T3 tumors. The elapsed treatment time was divided into < or = 7, 7.1-9, or > 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. Because of dose-escalation studies, 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 < or = 72 Gy with; elapsed treatment time had no impact. No pelvic failures were detected in 88 patients receiving doses > 72 Gy. In patients with T2 who received < or = 70 Gy, overall pelvic failure rate was 4% (12/306) in those with an elapsed treatment time of < or = 9 weeks, in contrast to 27% (12/44) for those with an elapsed treatment time > 9 weeks; at 10 years, patients with T2 tumors treated in > 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 prostate-specific antigen values whose tumors were stage T1c, the chemical failure rate was 41% (60/147) with a tumor dose < 70 Gy, compared with 17% (4/24) in those who received higher doses. In patients with stage 2 disease who were treated with < 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. Cause-specific survival without chemical failure in patients with stage T1c disease 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 < 9 weeks, in contrast to 65% for patients treated > 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 > 9 weeks in comparison with the failure and survival rates occurring with shorter times. Higher doses of irradiation (> 72 Gy) eliminate the influence of prolongation of treatment time on outcome.

Dose fractionation and biological optimization in carcinoma of the uterine cervix

Data of the literature concerning the dose, fractionation, and elapsed treatment time, all parameters critical to local pelvic tumor control in patients treated with irradiation for carcinoma of the cervix are analyzed. Total dose, dose rate, and biological dose optimization are important parameters that correlate with treatment sequelae. Elapsed treatment time does not. As for the use of brachytherapy, performance of all intracavitary insertions within the first 4.5 weeks of treatment correlated with better tumor control in stages IB, IIA and IIB with low dose rate (LDR) brachitherapy. Careful attention to biological parameters is critical to optimize treatment schemas and outcome of radiation therapy. When combinations of irradiation with either surgery or chemotherapy are used, special attention must be paid to tolerance doses of organs at risk, to minimize sequelae without compromising tumor control.

Dose fractionation and biological optimization in carcinoma of the prostate

Three-dimensional conformal radiation therapy (3-D CRT) or intensity-modulated radiation therapy (IMRT) have been increasingly used as an alternative to radical prostatectomy in patients with localized carcinoma of the prostate and in patients at high risk, in combination with hormonal therapy. To better understand the implications of dose-time and fractionation in prostate cancer, it is important to be familiar with some laboratory investigations dealing with the cell kinetics characteristics of this tumor. Biological and clinical considerations of dose fractionation, total dose of irradiation and local tumor control, elapsed overall treatment time and sequelae of irradiation are illustrated, based on an exhaustive review of the literature.

Radiation therapy for increasing prostate-specific antigen levels after radical prostatectomy

Herein we present data on outcomes in patients with increasing prostate-specific antigen (PSA) levels treated with irradiation to the pelvis and/or prostatic bed after radical prostatectomy. Between 1988 and 1998, 92 patients who presented with increasing PSA levels after radical prostatectomy were treated with irradiation, 29 to the pelvis and prostatic bed and 63 to the prostatic bed only. The mean follow-up was 4 years for the 3D-CRT group and 6.5 years for the standard radiation therapy group. Criterion for biochemical failure was an increase in post irradiation PSA level on > or = 1 consecutive measurement. Patients were classified into 3 risk groups based on prognostic factors: pathologic tumor extent and stage, Gleason score, and PSA levels before irradiation. Acute and late morbidity was quantitatively evaluated in all patients. There was a close correlation between the preirradiation PSA level and the probability of 4-year biochemical failure-free survival (75% with PSA levels < or = 1 ng/mL, 30% with PSA levels of 1.1-2 ng/mL, and 20% with PSA levels > 2 ng/mL; P = 0.05). The 4-year chemical failure rate was 20% in the low/intermediate-risk group and 65% in the high-risk group (P = 0.36). In 20 patients in the low-PSA group (< or =1 ng/mL) receiving doses > 62 Gy, no biochemical failures have been detected in comparison to a 70% failure rate at 4 years in patients treated with lower doses (P = 0.15). In the higher-PSA groups, no impact of irradiation dose on outcome was noted (40%-60% incidence of failure at 3 years). Pelvic irradiation was associated with a trend toward decreased biochemical failure rate in the low-PSA group (70% vs. 0% at 4 years; P = 0.35), but not in the high-PSA group. Only 1 patient (1.5%) experienced clinical local recurrence in the prostatic bed and 2 patients (1.8%) had distant metastases. Treatment has been very well tolerated, with only 3 patients in the arc-rotation group experiencing grade 2 treatment toxicity. Prostate bed irradiation is an effective treatment in a significant proportion of patients who present with a biochemical failure after radical prostatectomy.

Conservation Therapy in T1-T2 Breast Cancer

PURPOSE

To assess the significance of patient age, race, tumor-related prognostic parameters, status of surgical excision margins, and irradiation boost on incidence of ipsilateral breast relapse, and to review current issues in the management of T1-T2 breast cancer patients with conservation therapy.

MATERIALS AND METHODS

Records of 1037 patients with histologically confirmed stage T1 and 308 patients with T2 carcinoma of the breast treated with breast conservation therapy from January 1970 through December 1997 were prospectively registered and evaluated. The mean follow-up for surviving patients was 6.6 years (range, 4-30 years), with a minimum follow up of 4 years for all patients.

RESULTS

There were 78 ipsilateral breast relapses (IBRs); the actuarial 10-year incidence of IBR was 7% for T1 and 11% for T2 tumors. In patients 40 years of age or younger, four of 24 (17%) with extensive intraductal component developed an ipsilateral breast relapse, compared with six of 80 (8%) without extensive intraductal component, in contrast to eight of 159 (5%) and 33 of 776 (4%) in postmenopausal patients with or without extensive intraductal component, respectively. In patients with T2 tumors, two of eight (25%) women 40 years or younger with extensive intraductal component, and seven of 50 (14%) without extensive intraductal component developed ipsilateral breast relapse. The corresponding values for the patients older than 40 years were five of 48 (10%) and 13 of 202 (6%), respectively. The incidences of ipsilateral breast relapses, correlated with status of surgical margins after re-excision in T1 tumors, were one of 30 (3.3%) for positive, no relapses in 40 patients with close margins, 16 of 438 (3.6%) for negative, and 18 of 196 (9%) for undetermined margins. In the patients with T2 tumors, ipsilateral breast relapses occurred in two of 16 patients (12.5%) with positive margins, one of 16 (6%) with close, seven of 105 (6.6%)with negative, and four of 68 (5.9%) with undetermined margins (differences not statistically significant). In patients with T1 tumors, negative margins, the 10-year relapse rate was the same (8%) in 559 to whom a boost was administered and in 66 without a boost. In patients with positive margins, the relapse rate was 4% in 215 receiving a boost (18-20 Gy) and 33% (two of six) without a boost. In patients with T2 tumors and negative margins, the rate of ipsilateral breast relapses in 16 patients to whom no boost was given was 12%, as opposed to 10% in 143 patients who received a boost. However, with T2 tumors and close or positive margins, the IBR rate at 10 years was 12% in 81 given a boost, in contrast to 40% (2 of 5) without a boost. In T1 tumors, the breast failure rate was two of 53 (3.7%) in women < or = 40 years receiving chemotherapy and eight of 51 (15.6%) without chemotherapy. For T2 tumors, the corresponding values were seven of 39 (17%) and two of 19 (10.5%), respectively. In women 40 years or younger with T1 tumors receiving hormones or not, the ipsilateral breast relapse rate was two of 19 (10.5%) and eight of 85 (9.4%), respectively; in the older than 40 years group, the corresponding values were six of 377 (1.6%) and 35 of 558 (6.2%). In the patients with T2 tumors, ipsilateral breast relapse rates were not statistically different in the various groups. On multivariate analysis, only age and adjuvant therapy were significant factors predictive of ipsilateral breast relapse.

CONCLUSIONS

Surgical excision margins status following adequate doses of radiation therapy was not a predictor of ipsilateral breast relapse. In patients younger than 40 years of age with extensive intraductal component, a somewhat higher breast relapse rate was noted but not enough to preclude breast conservation therapy. A boost of irradiation did not have a significant impact in the incidence of ipsilateral breast relapse in patients with negative margins, but it was of benefit to those with close or positive margins. Close attention to surgical margin status and delivery of higher doses of irradiation to the tumor excision site in patients with close or positive surgical margins will decrease the probability of breast relapses.

Three-Dimensional Conformal Therapy Versus Standard Radiation Therapy in Localized Carcinoma of Prostate: An Update

This study updates technical principles and results of 3-dimensional conformal radiation therapy (3D-CRT) in localized carcinoma of the prostate. Between January 1992 and December 1999, 312 patients were treated with 3D-CRT and 135 patients were treated with bilateral arcs standard radiation therapy (SRT) alone for clinical stage T1b-c or T2 histologically confirmed prostate cancer. None of these patients received hormonal therapy. Mean follow-up for patients in the 3D-CRT group was 3.2 years (range, 2-5.9 years) and for SRT patients, 4.7 years (range, 4-7 years). For 3D-CRT, 7 intersecting fields were used (cerrobend blocking or multileaf collimation) to deliver 68-74 Gy to the prostate. Standard radiation therapy consisted of bilateral 120 degree rotational arcs, with portals using 2-cm margins around the prostate to deliver 68-70 Gy to the prostate. The criterion for chemical disease-free survival was a postirradiation prostate-specific antigen (PSA) value following the American Society for Therapeutic Radiology and Oncology guidelines. Symptoms during treatment were quantitated weekly, and late effects were assessed every 4-6 months. Dose-volume histograms showed a two-thirds reduction with 3D-CRT in normal bladder or rectum receiving > or = 70 Gy with 3D-CRT. Higher 5-year chemical disease-free survival was observed with 3D-CRT (75%; for T1b-c and 79%; for T2 tumors) compared with SRT (61% and 65%, P = 0.01 and P = 0.12, respectively). There was no statistically significant difference in chemical disease-free survival in patients with Gleason score of < or = 4 (P = 0.85), but, with Gleason score of 5-7, the 5-year survival rates were 83% with 3D-CRT and 59% with SRT (P < or = 0.01). In 245 patients with pretreatment PSA of < or = 10 ng/mL treated with 3D-CRT, the chemical disease-free rate was 80% versus 72% in 98 patients treated with SRT (P = 0.21). In patients with PSA of 10.1-20 ng/mL, the chemical disease-free survival rate for 50 patients treated with 3D-CRT was 71% compared with 43% for 20 patients treated with SRT (P = 0.02). The corresponding values were 59% and 16%, respectively, for patients with PSA levels > 20 ng/mL (P = 0.09). On multivariate analysis, the most important prognostic factors for chemical failure were pretreatment PSA (P = 0.004), nadir PSA (P = 0.001), and 3D-CRT technique (P = 0.012). Moderate dysuria was reported by 2%-5% of patients treated with 3D-CRT in contrast to 6%-9% of patients treated with SRT. The incidence of moderate loose stools or diarrhea, usually after the fourth week of treatment, was 3%-5% in the 3D-CRT patients and 8%-19% in the SRT group. Late intestinal grade 2 morbidity (proctitis or rectal bleeding) was 1% in the 3D-CRT group in contrast to 7% in SRT patients. The 3D-CRT spares more normal tissues, yields higher chemical disease-free survival, and results in less treatment morbidity than SRT in treatment of stage T1-T2 prostate cancer. Follow-up at > or = 10 years is needed to confirm these observations.

Functional imaging in treatment planning in radiation therapy: a review

The remarkable technical developments obtained in radiation oncology have resulted in an increasing use of image-based treatment planning in radiation therapy for three-dimensional and intensity modulated radiation therapy, stereotactic irradiation and image-guided brachytherapy. There has been increased use of computer-based record and verify systems as well as electronic portal imaging to enhance treatment delivery. From the data presented it is evident that PET scanning and other functional imaging techniques play a major role in the definition of tumor extent and staging of patients with cancer. The recent introduction of a combined CT and PET scanner will substantially simplify image acquisition and treatment planning.

Chemical disease-free survival in localized carcinoma of prostate treated with external beam irradiation: comparison of American Society of Therapeutic Radiology and Oncology Consensus or 1 ng/mL as endpoint

PURPOSE

To compare postirradiation biochemical disease-free survival using the American Society of Therapeutic Radiology and Oncology (ASTRO) Consensus or elevation of postirradiation prostate-specific antigen (PSA) level beyond 1 ng/mL as an endpoint and correlate chemical failure with subsequent appearance of clinically detected local recurrence or distant metastasis.

METHODS AND MATERIALS

Records of 466 patients with histologically confirmed adenocarcinoma of the prostate treated with irradiation alone between January 1987 and December 1995 were analyzed; 339 patients were treated with bilateral 120 degrees arc rotation and, starting in 1992, 117 with three-dimensional conformal irradiation. Doses were 68--77 Gy in 1.8 to 2 Gy daily fractions. Minimum follow-up is 4 years (mean, 5.5 years; maximum, 9.6 years). A chemical failure was recorded using the ASTRO Consensus or when postirradiation PSA level exceeded 1 ng/mL at any time. Clinical failures were determined by rectal examination, radiographic studies, and, when clinically indicated, biopsy.

RESULTS

Six-year chemical disease-free survival rates using the ASTRO Consensus according to pretreatment PSA level for T1 tumors were: < or = 4 ng/mL, 100%; 4.1--20 ng/mL, 80%; and > 20 ng/mL, 50%. For T2 tumors the rates were: < or = 4 ng/mL, 91%; 4.1--10 ng/mL, 81%; 10.1--20 ng/mL, 55%; 20.1--40 ng/mL, 63%; and > 40 ng/mL, 46%. When postirradiation PSA levels higher than 1 ng/mL were used, the corresponding 6-year chemical disease-free survival rates for T1 tumors were 92% for pretreatment PSA levels of < or = 4 ng/mL, 58--60% for levels of 4.1--20 ng/mL, and 30% for levels > 20 ng/mL. For T2 tumors, the 6-year chemical disease-free survival rates were 78% in patients with pretreatment PSA levels of 4--10 ng/mL, 45% for 10.1--40 ng/mL, and 25% for > 40 ng/mL. Of 167 patients with T1 tumors, 30 (18%) developed a chemical failure, 97% within 5 years from completion of radiation therapy; no patient has developed a local recurrence or distant metastasis. In patients with T2 tumors, overall 45 of 236 (19%) had chemical failure, 94% within 5 years of completion of radiation therapy; 4% have developed a local recurrence, and 10%, distant metastasis. In patients with T3 tumors, overall, 24 of 65 (37%) developed a chemical failure, 100% within 3.5 years from completion of radiation therapy; 4% of these patients developed a local recurrence within 2 years, and 12% developed distant metastasis within 4 years of completion of irradiation. The average time to clinical appearance of local recurrence or distant metastasis after a chemical failure was detected was 5 years and 3 years, respectively.

CONCLUSION

There was a close correlation between the postirradiation nadir PSA and subsequent development of a chemical failure. Except for patients with T1 tumors and pretreatment PSA of 4.1--20 ng/mL, there is good agreement in 6-year chemical disease-free survival using the ASTRO Consensus or PSA elevations above 1 ng/mL as an endpoint. Although the ASTRO Consensus tends to give a higher percentage of chemical disease-free survival in most groups, the differences with longer follow-up are not statistically significant (p > 0.05). It is important to follow these patients for at least 10 years to better assess the significance of and the relationship between chemical and clinical failures.