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.

Clinical assessment of outcome of prostate cancer (TCP, NTCP)

In the recent past there have been major advances in the management of patients with prostate cancer. New imaging procedures as 3-D CRT and IMRT have played a major role in the tretament of patients with localized prostate cancer. 3-D CRT allows higher doses to be delivered more precisely to the target volume with acceptable organs at risk morbidity. Improved tumor control results in lower incidence of distant metastases and better survival with an enhanced quality of life. This outcome yields a lower cost per treatment of patients over their life time.

Uncertainties in radiation therapy: target definition in carcinoma of the uterine cervix

In treatment of patients with carcinoma of the cervix, as in any other malignant tumor, accurate identification of target volumes is critical to enhance precision of radiation therapy planning and delivery. These results in improved locoregional tumor control lead to lower incidence of distant metastases and improved survival. Also, radiation therapy morbidity is decreased, enhancing quality of life. Various imaging techniques are available to achieve better target delineation and this can be enhanced with image fusion. Available innovative treatment techniques to optimize the use of radiation therapy for these patients are illustrated.

Radiation therapy in the treatment of localized prostate cancer: an alternative to an emerging consensus

Optimal treatment for patients with localized carcinoma of prostate is controversial. Radiation therapy is an established modality; reports indicate that results are comparable to those of radical prostatectomy. A retrospective review was carried out of 963 patients with carcinoma of the prostate treated with definitive irradiation (65 to 71 Gy in 6.5 to 7 weeks). Survival, incidence of local recurrence and distant metastases, and postirradiation PSA data were analyzed. Ten-year disease-free survival with external irradiation was 100% for clinical stage A1 (T1a), 69% for stage A2 (T1b,c), 57% for clinical stage B (T2), and 41% for stage C (T3). Initial PSA level closely correlated with probability of freedom from chemical failure (PSA elevation) after definitive irradiation in 317 patients with stage T1b,c and T2 tumors (96% and 89%, respectively, with initial PSA of < 10 ng/ml and 75% and 65% with higher PSA levels). Although modern irradiation techniques produce results comparable to those of radical prostatectomy in localized prostate carcinoma, we must continue to critically assess treatment policies, develop appropriately designed prospective clinical trials, and define optimal management of these patients.

Treatment planning in radiation oncology and impact on outcome of therapy

Irradiation is effective treatment for many patients with cancer. It can completely eradicate the tumor in the irradiated volume or it provides palliative relief to patients with incurable cancer. The success of radiation therapy depends on the delivery of an adequate dose to the entire tumor volume with acceptable morbidity in the surrounding normal tissues. The goals are to achieve the highest probability of local and regional tumor control with the lowest achievable incidence of side effects and to prolong the life of the patient with the best possible quality of life. Although treatment planning is extremely helpful in determining the best form of therapy, the responsibility for critical judgment and execution rests with the radiation oncologist, who, to treat patients effectively, must have sufficient training to define the target volume and critical structures, to interpret treatment planning information and to guide the physicist or dosimetrist in achieving the best dose distribution; have sufficient knowledge to select the best possible combination of dose and fractionation for a given site and volume; be competent to judge the quality of the dose distribution and the technical feasibility and accuracy of proposed plan; and understand the capabilities and limitations of the staff and computer systems involved in the radiation treatment planning process. No computer software can correct the radiation oncologist's errors of clinical judgment, misunderstanding of physical concepts, or inadequate treatment delivery.

Thermal dose expression in clinical hyperthermia and correlation with tumor response/control

Thermal dose has been identified as one of the most important factors which influence the efficacy of hyperthermia. Adequate temperature must be delivered for an appropriate period of time to the entire tumor volume in order to achieve optimal therapeutic results. Present clinical thermometry systems provide coarse temperature readings, since only selected tumor or normal tissue temperatures are monitored. Experimental in vitro and in vivo data suggest that the minimal temperature observed in the tumor determines therapeutic effectiveness. Unfortunately, at the present time, clinical data documenting these observations are scarce. The inhomogeneity of temperature distribution throughout the tumor volume makes difficult accurate correlations with tumor response and subsequent tumor control. Several mathematical models have been offered to express the time-temperature equivalency in relation to a reference temperature (43 degrees equivalent). Factors such as step-down heating, fractionated hyperthermia, thermal adaptation, and combination with irradiation, in addition to physiological parameters such as blood flow, play a major role in the expression of thermal dose. In order to meaningfully express thermal dose in clinical hyperthermia, several procedures are recommended, such as static phantom studies of specific absorption rate distributions for heat delivery equipment, detailed thermal mapping in hyperthermia sessions, development of reliable predictive biomathematical models to express temperature-time equivalency, and the fostering of research in 3-dimensional noninvasive clinical thermometry.

Methodology of research and practice for the third millennium: evidence-based medicine

In the past 10 years there have been significant scientific advances in biological sciences and health care. The growth in basic and translational research data to guide medical practice, which has an impact on health care costs has made it critical for clinicians to appraise and use published evidence for medical decisions. Evidence-based medicine should be strengthened and promoted to enhance the rationale and quality of medical care provided to our patients. Basic laboratory research and properly designed, relevant and timely prospective clinical trials should be strongly supported; patient participation must be increased to acquire more accurate information to develop innovative therapeutic strategies in oncology. New avenues in cancer detection and staging, as well as therapy, suggested by basic and translational laboratory research, must be vigorously pursued and adequately funded. Methodology for accurate cost accounting of medical care and cost-benefit studies needs further development. Technology assessment will substantially contribute to better utilization of scarce health care resources.

New trends in prostatic cancer research. Three-dimensional conformal radiation therapy (3-D CRT), brachytherapy, and new therapeutic modalities

In prostatic cancer research three-dimensional conformal radiation therapy (3-D CRT), brachytherapy and new therapeutic modalities have been applied. Treatment planning and delivery of radiation therapy have substantially evolved in the past 20 years. The treatment of localized carcinoma of the prostate with 3-D CRT is described, preliminary clinical results are presented and compared with those with standard radiation therapy (SRT). The benefit of 3-D CRT hypothetically could be linked to improved local tumor control because of a better coverage of the target volume with a specific dose of irradiation, less acute and late toxicity, possibility of carrying out dose-escalation studies. Intensity modulated radiation therapy (IMRT) may be particularly useful in some cases. Further efforts are necessary with collaboration of urologists and radiation oncologists to continue to explore approaches to optimally select and manage patients with localized prostate cancer. A reliable assessment of the impact of 3-D CRT and IMRT on outcome should come from prospective randomized long-term studies. As for brachytherapy, standardized protocols should be developed to objectively evaluate brachytherapy in localized prostatic cancer. Recently a great deal of interest has been focused on new therapeutic modalities with chemotherapeutic agents, a new agent named prostate specific enhancer, a regulatory element of the PSA gene is being tested. Laboratory and animal studies of the viral construct have been reported. A phase I human clinical trial is being initiated in the U.S.A. in patients with postirradiation hormone refractory prostate cancer.

Role of radiation therapy for locally advanced and inflammatory carcinoma of the breast

In patients with locally advanced or inflammatory breast cancer, irradiation and radical or modified radical mastectomy yield equivalent local-regional control. However, even when combined with modern chemotherapy, at least 30% of patients will suffer local-regional failure when only one local modality is used. Increased local control (to 85%-95%), with fewer complications, can be achieved when surgery and radiotherapy are combined.

Radiation therapy in the management of carcinoma of the ovary

The results in 212 patients treated with radiation therapy for various stages of carcinoma of the ovary are reported. The role of radiation therapy in the management of these patients is analyzed in the light of available data. Radiation therapy may improve the survival of patients with stage I ovarian cancer (with poorly differentiated lesions or extension through the capsule) and the survival of patients with stage II ovarian tumors. The patients with stage III ovarian lesions may benefit by a combination of irradiation and chemotherapy. A multidisciplinary approach to ovarian carcinoma must be promptly established, with participation of gynecologic surgeons, radiation therapists, pathologists, and chemotherapists. More thorough staging procedures and well-defined pathologic classifications are necessary. The biologic and pathologic behavior of these tumors must be further elucidated. The limitations of each treatment method must be exactly defined. Based on this information, rational treatment schemes may be formulated. Controlled clinical trials are necessary to evaluate the effectiveness of optimal surgery, irradiation, and chemotherapy, or their combinations.

Radiation therapy in the multimodal management of Ewing's sarcoma of bone: report of the Intergroup Ewing's Sarcoma Study

This paper is a progress report on the role of radiation therapy (RT) in local tumor control and the decreased incidence of pulmonary metastasis in 251 patients entered in the Intergroup Ewing's Sarcoma Study. All were followed for more that 1 year, and their RT records were reviewed. Doses to the primary tumor in the range of 4,500--6,500 rad were administered over approximately 5 to 6 weeks in combination with 4 drugs, i.e., vincristine (VCR), dactinomycin (DAC), cyclophosphamide (CY), and adriamycin, or only the first 3. One group of patients received the 3 drugs and bilateral pulmonary irradiation (approximately 1,500 rad in 2 wk). Preliminary analysis showed a local primary tumor control of approximately 90%. Patients with lesions in the pelvis and humerus had local failure rates of 13% (7 of 54) and 21.4% (6 of 28), respectively. The treatment groups differed significantly in the incidence of pulmonary metastasis. Patients treated with the 4 drugs (regimen 1) had a 14% incidence, whereas 42% of those treated with only 3 drugs (regimen 2) developed pulmonary metastases. Of all patients treated with 3 drugs and pulmonary irradiation (regimen 3), 18% showed lung metastases. The study indicated that intensive chemotherapy and RT significantly improved the local control and survival of patients with localized Ewing's sarcoma. However, the high incidence of metastasis indicated the need for more effective systemic chemotherapy for further improvement of treatment results. More studies are needed so we can define the volume to be treated and the optimal dose of irradiation to determine a therapeutic strategy that will yield optimal survival and tumor control with the fewest sequelae.