Total body irradiation before bone marrow transplantation. Technique and acute toxicity

PURPOSE

To evaluate the total body irradiation methods in the National Institute of Oncology between January 1984 and February 1998.

PATIENTS AND METHODS

One hundred and twenty-four patients underwent total body irradiation prior to bone marrow transplantation in the last 15 years. A special cobalt unit has been used, the dose rate was 6 to 8 cGy/min in the midline of the abdomen. The source-midline distance (SMD) was 340 cm and the field size was 80 x 200 cm. The dose calculation was done on the basis of a tissue-phantom ratio curve measured in total body irradiation conditions and effective tissue thickness (ETT). Between 1984 and 1992 the beam direction was horizontal, the patients laid in lateral position. In 11 cases the total dose to the abdominal midline was 10 Gy in 1 fraction. From 1986 the fractionation changed to 4 x 3 Gy in 4 days. Within individual lung shielding the average lung dose was 8.5 Gy. In 44/124 cases the order of conditioning treatment was chemo-radiotherapy. Since 1992 vertical beams were used, and the patients (80/124) laid in prone/supine position. The fractionation remained the same but radio-chemotherapy regime has been used.

RESULTS

The irradiation in prone position proved to be safer than lateral because of smaller patient motion and it resulted in a more accurate positioning of lung shielding too. In all cases, the acute side effects (headache, nausea, vomiting) were moderate. Using radio-chemotherapy the acute side effects during the total body irradiation were uncommon and well tolerable.

CONCLUSION

Our technique with the large source-midline distance, vertical beam direction and the supine/prone position is stable, convenient and safe to produce homogeneous dose distribution and ensures accurate and reproducible lung shielding.

[Radiologic follow-up after breast-conserving surgery: value of MRI examination of the breast]

The aim of the study was to establish an objective method for evaluation the extent, topography and quantity of skin and soft tissue side effects after tele- and/or brachyradiotherapy of the conserved breast and to compare the sequales of different radiation methods. 26 patients operated on for T1-2 N0-1 breast cancer underwent the following kinds of postoperative radiotherapy: 1. 46-50 Gy whole breast teletherapy + 10-16 Gy electron boost (5 patients), 2. 46-50 Gy teletherapy + 10-15 Gy HDR brachytherapy boost (12 patients), 3. 46-50 Gy teletherapy (6 patients), 4. 36,4 Gy sole HDR brachytherapy of the tumour bed (5 patients). The postirradiation side effects were examined by MRI, mammogram, US and physical examination, as well. MRI was performed on a 0.5 T, double breast coil, with SE-T1, SE-T2 and 3D-GE sequences. The findings of MRI and mammography were compared to physically detectable side effects using the RTOG/EORTC late radiation morbidity scoring scheme. US is useful in the measurement of skin thickening and in the diagnosis of fat necrosis. Mammography and physical examination are very subjective and low specificity methods to evaluate postirradiation side effects. MRI is a suitable and more objective method to detect the real extent and quantity of skin thickening and fibrosis. The incidence of > or = G2 side effects of skin and breast parenchyma were 64.5 and 32.2%, respectively. The differences between the side effects of whole breast irradiation and sole brachytherapy of the tumour bed are also clearly demonstrated. Brachytherapy alone is feasible without compromising cosmetic results. The authors established the MRI criteria for categorization the extent and grade of skin thickening and fibrosis (focal vs diffuse, grade 1-4). Breast MRI is an objective tool for assisting to the evaluation of the side effects of postoperative radiotherapy.

Intra-arterial preoperative cytostatic treatment versus preoperative irradiation: A prospective, randomized study of lingual and sublingual carcinomas

BACKGROUND

For several decades, both preoperative intra-arterial chemotherapy and preoperative irradiation have been accepted treatments for patients with tumors of the head and neck. Unfortunately, arguments have often been put forward in favor of one or other of the two methods, but without the performance of an objective, randomized investigation. To resolve this situation, the authors have carried out a multicenter, randomized prospective study of selected patients with a view to deciding which method affords better results in complex tumor therapy from the aspects of survival and postoperative quality of life.

METHODS

One hundred thirty-one patients with operable sublingual or lingual squamous cell carcinoma in stages T2NXM0 to T4MXM0 were randomized into 2 groups: 1 group participated in preoperative chemotherapy with cisplatin and epirubicin (total doses: 200 mg cisplatin, 120 mg epirubicin) via the external carotid artery, whereas the other group received preoperative radiation therapy (46 grays). Following subsequent radical surgery, the patients received regular follow-up for 5 years.

RESULTS

By the end of the 5 years, 95 of the 131 patients had conformed to the protocol. Of those 95, 47 had received preoperative chemotherapy and 48 preoperative irradiation. After 5 years, 18 of the 47 patients who received chemotherapy and 15 of the 48 patients who received irradiation were still alive and tumor free. A few more patients had died of recurrence or regional metastasis in the chemotherapy group (23 patients) than in the irradiation group (20 patients). Occurrence of a second carcinoma was 3 times as frequent in the irradiation group (9 patients) as in the chemotherapy group (3 patients). Overall, the survival rates were by-and-large the same for the two groups. Regarding postoperative quality of life, the chemotherapy group presented a more favorable picture.

CONCLUSIONS

The long term survival results subsequent to preoperative intra-arterial chemotherapy or preoperative radiotherapy were practically the same. Regarding postoperative quality of life, patients who underwent intra-arterial chemotherapy appeared to be in a slightly more favorable situation. The authors consider it important to stress these findings, as they are not aware of a similar randomized study of patients with tumors of the oral cavity.

Reliability of EMG spectral parameters in repeated measurements of back muscle fatigue

The change in median frequency of the power spectrum of the electromyographic (EMG) signal may be used as a measure of muscle fatigue. The reliability of the median frequency parameters was investigated for EMG-recording sites at L1 and L5 right and left on the erector spinae. The reliability of subjective fatigue ratings of the back muscles (Borg CR-10 scale) and of maximal trunk extension torque (MVC) was also investigated. Eleven subjects with healthy backs performed a 45-s isometric trunk extension at 80% of MVC twice a day, on three different days. Two-factor analysis of variance was made to obtain the different variances from which the standard error of measurement (SEM) and the intra class correlation coefficient (ICC) were calculated. The SEM within-day was somewhat lower than that between-days. Both were about the same at all four electrode sites. The 95% confidence interval for the studied variables was for the initial median frequency +/- 10 Hz, for the slope +/- 0.4-0.5%/s, for the MVC +/- 36 Nm and for the Borg ratings +/- 1.6. We conclude that, with the presently used method, changes or differences within these limits should be regarded as normal variability. The slope may be of limited value because of its large variability. Whether the low intraclass correlation coefficient for the EMG parameters in the presently studied test group implies a low potential in discriminating subjects with back pain can not be decisively concluded.

Acute low-back-pain patients exhibit a fourfold increase in sick leave for other disorders: a case-control study

One hundred eighty patients with acute low-back pain (LBP) were compared to 608 age- and sex-matched controls with regard to somatic and personality characteristics. The low-back-pain group had a fourfold increase (median) in sick-leave episodes for reasons other than spinal morbidity during the preceding 2 years. In the same period, the median number of episodes of sick leave for LBP was 1 in the patients and 0 in the controls. The mean number of days off for other reasons was 34 (median = 20.5) in the patients compared to 9 (median = 0) in the controls, and days off for LBP were 20 (median = 5) and 5 (median = 0), respectively. Analysis of other factors than those directly related to LBP disclosed significant differences in marital status and smoking habits between patients and controls. Furthermore, LBP patients estimated their work to be physically heavier. We conclude that medical intervention should focus not only on the spine, but also on a wide range of other aspects of the patient's situation. Even in the acute phase of LBP, the previous sick-leave records should be analyzed to provide adequate measures to prevent future sick leaves. Presently, the sociomedical costs for a subset of the population who repeatedly seek help for LBP are significantly higher than those for the non-LBP population.

[Brachytherapy of the tumor bed after breast conserving surgery: new radiotherapeutic option in the management of early breast cancer]

PURPOSE

To initiate fractionated, interstitial high dose rate brachytherapy of the tumour bed as the sole radiation modality after breast conserving surgery.

PATIENTS AND METHODS

In 41 cases of selected stage I-II breast cancer the tumour bed was marked with titanium clips during breast conserving surgery. The tumour bed was implanted with flexible plastic catheters to deliver postoperative radiotherapy. In 8 cases 7 x 4.33 Gy (30.3 Gy), in 33 cases 7 x 5.2 Gy (36.4 Gy) interstitial 192Ir high dose rate brachytherapy was given to the clipped area. Irradiation of the whole conserved breast was omitted. The radiation side effects were assessed by mammograms and MRI-examinations.

RESULTS

At a median follow up of 17 (4-36) months neither distant nor regional failure was observed. Local recurrence was detected in 1/41 (2.4%) case. G2 radiation side effects were observed in 2/21 (9.5%).

CONCLUSIONS

Postoperative sole brachytherapy of the tumour bed with careful patient selection and adequate quality assurance seems to be a feasible alternative to whole breast teletherapy. Sole brachytherapy shortens the time of radiotherapy from 5-6 weeks to 5 days, and reduces the costs of treatment. The skin and volume sparing effect of interstitial irradiation may decrease the side effects of radiotherapy.

External audit on the clinical practice and medical decision-making at the departments of radiotherapy in Budapest and Vienna

PURPOSE

To present an example of how to study and analyze the clinical practice and the quality of medical decision-making under daily routine working conditions in a radiotherapy department, with the aims of detecting deficiencies and improving the quality of patient care.

METHODS

Two departments, each with a divisional organization structure and an established internal audit system, the University Clinic of Radiotherapy and Radiobiology in Vienna (Austria), and the Department of Radiotherapy at the National Institute of Oncology in Budapest (Hungary), conducted common external audits. The descriptive parameters of the external audit provided information on the auditing (auditor and serial number of the audit), the cohorts (diagnosis, referring institution, serial number and intention of radiotherapy) and the staff responsible for the treatment (division and physician). During the ongoing external audits, the qualifying parameters were (1) the sound foundation of the indication of radiotherapy, (2) conformity to the institution protocol (3), the adequacy of the choice of radiation equipment, (4) the appropriateness of the treatment plan, and the correspondence of the latter with (5) the simulation and (6) verification films. Various degrees of deviation from the treatment principles were defined and scored on the basis of the concept of Horiot et al. (Horiot JC, Schueren van der E. Johansson KA, Bernier J, Bartelink H. The program of quality assurance of the EORTC radiotherapy group. A historical overview. Radiother. Oncol. 1993,29:81-84), with some modifications. The action was regarded as adequate (score 1) in the event of no deviation or only a small deviation with presumably no alteration of the desired end-result of the treatment. A deviation adversely influencing the result of the therapy was considered a major deviation (score 3). Cases involving a minor deviation (score 2) were those only slightly affecting the therapeutic end-results, with effects between those of cases with scores 1 and 3. Non-performance of the necessary radiotherapeutic procedures was penalized by the highest score of 4. Statistical evaluation was performed with the BMDP software package, using variance analysis.

RESULTS

Bimonthly audits (six with a duration of 4-6 h in each institution) were carried out by three auditors from the evaluating departments; they reviewed a total of 452 cases in Department A, and 265 cases in Department B. Despite the comparable staffing and instrumental conditions, a markedly higher number (1.5 times) of new cases were treated in Department A, but with a lower quality of radiotherapy, as adequate values of qualifying parameters (1-6) were more frequent for the cases treated in Department B (85.3%, 94%, 83.4%, 28.3%, 41.9% and 81.1%) than for those in Department A (67%, 83.4%, 87.8%, 26.1%, 33.2% and 17.7%). The responsible division (including staff and instrumentation), the responsible physician and the type of the disease each exerted a highly significant effect on the quality level of the treatment. Statistical analysis revealed a positive influence of the curative (relative to the palliative/symptomatic) intention of the treatment on the level of quality, but the effect of the first radiotherapy (relative to the second or further one) was statistically significant in only one department. At the same time, the quality parameters did not vary with the referring institution, the auditing person or the serial number of the audit.

CONCLUSION

The external audit relating to the provision of radiotherapeutic care proved feasible with the basic conformity and compliance of the staff and resulted in valuable information to take correction measures.

[Evaluation of the effectiveness of radiotherapy in an Austrian-Hungarian collaboration]

To present an example of how to study and analyse the clinical practice and the quality of medical decision-making under daily routine working conditions in a radiotherapy department, with the aims of detecting deficiencies and improving the quality of patient care. Bimonthly audits (6 with a duration of 4-6 hours in each institution) were carried out by 3 auditors from the evaluating departments; they reviewed a total of 452 cases in Department A, and 265 cases in Department B. During the ongoing external audits, the qualifying parameters were (1) the sound foundation of the indication of radiotherapy, (2) the conformity to the institution protocol (3), the adequacy of the choice of radiation equipment, (4) the appropriateness of the treatment plan, and the correspondence of the latter with (5) the simulation and (6) verification films. Various degrees of deviation from the treatment principles were defined and scored on the basis of the concept of Horiot et al. (10), with some modifications. The action was regarded as adequate (score 1) in the event of no deviation or only a small deviation with presumably no alteration of the desired end-result of the treatment. A deviation adversely influencing the result of the therapy was considered a major deviation (score 3). Cases involving a minor deviation (score 2) were those only slightly affecting the therapeutic end-results, with effects between those of cases with scores 1 and 3. Non-performance of the necessary radiotherapeutic procedures was penalized by the highest score of 4. Statistical evaluation was performed with the BMDP software package, using variance analysis. Despite the comparable staffing and instrumental conditions, a markedly higher number (1.5 times) of new cases were treated in Department A, but with a lower quality of radiotherapy, as adequate values of qualifying parameters (1)-(6) were more frequent for the cases treated in Department B (85, 94%, 83%, 28%, 42% and 81%) than for those in Department A (67%, 83%, 88%, 26%, 33% and 18%). The responsible division (including staff and instrumentation), the responsible physician and the type of the disease each exerted a highly significant effect on the quality level of the treatment. Statistical analysis revealed a positive influence of the curative (relative to the palliative/symptomatic) intention of the treatment on the level of quality, but the effect of the first radiotherapy (relative to the second or further one) was statistically significant in only one department. The external audit related to the provision of radiotherapeutic care proved feasible with real valuation of the staff's activity.

Correlation between electromyographic spectral changes and subjective assessment of lumbar muscle fatigue in subjects without pain from the lower back

OBJECTIVE

The purpose of this study was to correlate objective measurements of muscle fatigue in the lower back to the subject's own assessment of fatigue.

DESIGN

Muscle fatigue in the lower back was assessed in healthy subjects using electromyography (EMG), endurance time and the Borg scale.

BACKGROUND

Muscle fatigue, measured with EMG and endurance time, in the lower back, is significant for patients with pain in the lower back.

METHODS

Fifty healthy subjects participated. EMG was detected from the lumbar extensor muscles during a modified Sørensen's test, an isometric contraction for the back extensors until exhaustion. During the test, subjects rated their subjective fatigue on a Borg CR-10 scale.

RESULTS

Borg scale ratings correlated with endurance time (0.68) and EMG median- and mean power frequency slopes (0.41-0.50). At a Borg rating of 3, median- and mean power frequency and endurance time were reduced by 30%. At a Borg rating of 5, median- and mean power frequency and endurance time were reduced by 50%. At a Borg rating of 7, median- and mean power frequency and endurance time were reduced by 60-70%.

CONCLUSIONS

Significant correlation between the Borg scale, EMG and endurance time suggests a close relationship between subjective and objective assessment of muscle fatigue.

Conservative treatment in patients sick-listed for acute low-back pain: a prospective randomised study with 12 months' follow-up

We evaluated three different conservative treatment methods for acute low-back pain patients in groups following a manual therapy programme, an intensive training programme, or a general practitioner programme, the latter serving as the control group. Patients aged 19-64 years on sick leave for low-back pain with or without sciatica were included in a prospective randomised study evaluating outcomes such as impairment, pain, functional disability, socio-economic disability and satisfaction with the treatment or explanations. Evaluation by unbiased observers was performed at 1, 3 and 12 months. The three treatment groups were comparable at baseline. With regard to satisfaction, the patients in the manual therapy programme and those in the intensive training programme were more satisfied with the treatment than those in the general practitioner programme at all follow-ups. With regard to the explanations of current low-back pain episodes, the patients in the manual therapy programme were more satisfied than those in the general practitioner programme at all follow-ups. The manual therapy programme group were also more satisfied with the explanations than those in the intensive training programme at the 1-month follow-up. However, no differences were revealed between the groups with respect to outcomes on measures of impairment, pain, functional disability or socioeconomic disability. All three study groups showed rapid improvement. After 1 month a significant improvement was noted in all outcome values compared with the values on entry to the study. Within the limitations discussed in our study, it is concluded that (1) patients sick listed with acute low-back pain, with or without sciatica, will be significantly improved after 1 month regardless of conservative treatment programme; (2) they will be more satisfied with the treatment if they are referred to a manual treatment programme or a training treatment programme; (3) they will be more satisfied with the explanations of the acute low-back problem if they are referred to one of the above groups, especially the manual treatment group; (4) they will not show any other differences with respect to subjective and objective variables, either at short-term or at long-term follow-ups.

A model predicting individual shoulder muscle forces based on relationship between electromyographic and 3D external forces in static position

To study the potentiality for developing an EMG-based model for the human shoulder, mapping of relations between static hand forces and electromyographic (EMG) activity of 13 shoulder muscles, were performed. The procedure was to perform by the hands slowly varying isometric forces up to 20% maximum voluntary force in the three-dimensional space. By combining these data with literature values on muscle physiological cross-sectional area and moment arm data, an EMG-based model was developed for estimating muscle forces in the glenohumeral joint. The model was validated for one standardized position by comparing joint moment, calculated from EMG by using the model, with moments from the external force. The highest correlation between these moments was found assuming a linear EMG/force calibration at low force level (< 20% MVC), giving correlations from 0.65 to 0.95 for the abduction/adduction moment and from 0.70 to 0.93 for the flexion/extension moment, for the six subjects. Moments calculated from EMG were for most subjects somewhat lower than the moments from the external force; the mean residual error ranged from 1.6 to 9.9 Nm. Taking this into account, the results can be used for assessment of muscle forces based on recordings of external forces at the hands during submaximal static work tasks without substantially elevated arms.

[Pain analysis is vital in rheumatic diseases. Pain often causes much worry to patients]

The article consists of a synthesis of a rheumatic pain symposium held at the annual meeting of the Swedish Medical Association in 1996. Various aspects of pain in rheumatic diseases were discussed, such as physiological, neurohumoral and neurogenic mechanisms, sensory stimulation treatment, differentiation of mechanical and inflammatory pain, quality enhancement by improved co-operation between primary and tertiary care facilities, pharmacological treatment with (centrally and peripherally acting) opioids, selective cyclo-oxygenase inhibitors, and NMDA (N-methyl-D-aspartate) receptor antagonists. For patients with rheumatic disorders exacerbated by pain problems, as for other patients, a pain diagnosis is of fundamental importance. This can be achieved by analysis of the social, psychological, physiological and medical factors contributing to the cause and degree of pain and to pain behaviour, and of the extent to which the pain may be nociceptive (i.e., inflammatory, mechanical, or ischaemic in origin), neurogenic or idiopathic. Pain analysis should be followed by individualised treatment focused on the patient's most crucial problems, thus enhancing the prospect of optimal treatment outcome.

[Pain analysis is vital in rheumatic diseases. The pain is often the patient's worst problem]

The article consists of a synthesis of a rheumatic pain symposium held at the annual meeting of the Swedish Medical Association in 1996. Various aspects of pain in rheumatic diseases were discussed, such as physiological, neurohumoral and neurogenic mechanisms, sensory stimulation treatment, differentiation of mechanical and inflammatory pain, quality enhancement by improved cooperation between primary and tertiary care facilities, pharmacological treatment with (centrally and peripherally acting) opioids, selective cyclo-oxygenase inhibitors, and NMDA (N-methyl-D-aspartate) receptor antagonists. The aim of the symposium, with its focus on the manifest pain problem, was to improve our knowledge and skill in the understanding and treatment of this large patient category. For patients with rheumatic disorders exacerbated by pain problems, as for other patients, a pain diagnosis is of fundamental importance. This can be achieved by analysis of the social, psychological, physiological and medical factors contributing to the cause and degree of pain and to pain behaviour, and of the extent to which the pain may be nociceptive (i.e., inflammatory, mechanical, or ischaemic in origin), neurogenic or idiopathic. Pain analysis should be followed by individualised treatment focused on the patient's most crucial problems, thus enhancing the prospect of optimal treatment outcome.

[The observation of edema in the substantia alba during postoperative brain irradiation. The role of computed tomographic studies]

BACKGROUND

The aim of our study was to determine on CT whether a relation exists between a radiation-induced brain edema, treated with diuretics and its corresponding Houndsfield Units (HU).

PATIENTS AND METHODS

Seventy-five patients (age 20 to 65 years, suffering from headaches but without hypertension brain tumors or cerebral arteriosclerosis were examined as a reference group. Three slices with 8 mm thickness, 24 mm apart in the upper, middle and lower third of the brain were obtained to measure the HU of the white matter. The second group consisted of 20 patients with brain tumors, which underwent brain surgery. HU of the white matter were measured before radiation and after 10, 20, 30, 40 and 50 Gy. If a reduction in density was detected, diuretic therapy with 40 mg furosemide per o.s. was initiated. If no increase in density was found on follow-up additional therapy with glycerine (4.5 g/kg body weight) was started. In this cases follow-up was on day 4 after initiation of diuretics. If clinical symptoms suggested an increasing in intracranial pressure, CT-examination was performed immediately. Therapy was started according to measurement results. The third group consisted of 64 patients with brain tumors, that underwent postsurgical radiation therapy. Prior to radiation therapy 40 mg furosemide per o.s. were given. CT-examinations, intensified diuretic therapy and follow-up examinations were performed as in group 2. If, despite therapy, the HU decreased, infusion of mannites was added. The second and third group of patients received radiation therapy with telecobalt and/or a linear accelerator (6 and 9 MeV X-ray).

RESULTS

In the first group white matter density was > 30 HU. In the second group white matter density was between 25 and 29 HU prior to diuretic therapy. Under 25 HU a continuous headache, vertigo and confusion ensued. Diuretic therapy was intensified until the measured values reached 25 to 29 HU. Forty-seven of 64 patients in the third group had 25 to 29 HU prior to radiation therapy. Despite prophylactic diuretic therapy in 28 cases density decreased to 20 to 24 HU. Improvement was achieved with an additional glycerine per o.s. The measured values reached again 25 to 29 HU. In 1 case the values dropped under 20 HU. Additional mannite infusion was necessary. In 17 of 64 patients white matter density was > 30 HU prior to radiation therapy, dropping to 25 to 29 HU during radiation. Prophylactic diuretic administration kept the values in this range. A correlation between age of the patient, radiation source, total dose, tumor histology and degree of change in HU was not found.

CONCLUSION

Measurements of HU can serve as a good indicator for spontaneous or diuretic induced changes of a white matter edema during radiation therapy.

Electromyographic activity in expert downhill skiers using functional knee braces after anterior cruciate ligament injuries

We studied six expert downhill skiers who had sustained anterior cruciate ligament injuries and had different degrees of knee instability. The aim was to measure possible changes in electromyographic activity recorded from lower extremity muscles during downhill skiing in a slalom course without and with a custom-made brace applied to the injured knee. Surface electrodes were used with an eight-channel telemetric electromyographic system to collect recordings from the vastus medialis, biceps femoris, semimembranosus, semitendinosus, and gastrocnemius medialis muscles from both legs. Without the brace, the electromyographic activity level of all muscles increased during knee flexion. The biceps femoris muscle was the most activated and reached 50% to 75% of the maximal peak amplitude. With the brace, the electromyographic activity increased in midphase during the upward push for the weight transfer and the peak activity occurred closer to knee flexion in midphase. Also, the uninjured knee was influenced by the brace on the injured leg, a decrease in electromyographic activity was seen in midphase. Spearman's rank correlation revealed a significant correlation between an increase in biceps femoris activity of the injured leg and increasing knee instability. We suggest that the brace caused an increased afferent input from proprioceptors, resulting in an adaptation of motor control patterns secondarily modifying electromyographic activity and timing.

Survival chance in papillary thyroid cancer in Hungary: individual survival probability estimation using the Markov method

PURPOSE

The typically benign, but occasionally rapidly fatal clinical course of papillary thyroid cancer has raised the need for individual survival probability estimation, to tailor the treatment strategy exclusively to a given patient.

MATERIALS AND METHODS

A retrospective study was performed on 400 papillary thyroid cancer patients with a median follow-up time of 7.1 years to establish a clinical database for uni- and multivariate analysis of the prognostic factors related to survival (Kaplan-Meier product limit method and Cox regression). For a more precise prognosis estimation, the effect of the most important clinical events were then investigated on the basis of a Markov renewal model. The basic concept of this approach is that each patient has an individual disease course which (besides the initial clinical categories) is affected by special events, e.g. internal covariates (local/regional/distant relapses). On the supposition that these events and the cause-specific death are influenced by the same biological processes, the parameters of transient survival probability characterizing the speed of the course of the disease for each clinical event and their sequence were determined. The individual survival curves for each patient were calculated by using these parameters and the independent significant clinical variables selected from multivariate studies, summation of which resulted in a mean cause-specific survival function valid for the entire group. On the basis of this Markov model, prediction of the cause-specific survival probability is possible for extrastudy cases, if it is supposed that the clinical events occur within new patients in the same manner and with the similar probability as within the study population.

RESULTS

The patient's age, a distant metastasis at presentation, the extent of the surgical intervention, the primary tumor size and extent (pT), the external irradiation dosage and the degree of TSH suppression proved to be statistically significant and independent prognostic factors with regard to cause-specific survival in multivariate studies. During follow-up, 14, 14, 9 and 12% of the patients underwent local/regional/distant relapses or thyroid cancer-related death, respectively. Through use of the above six independent clinical variables and the parameters relating to the four clinical events and their interrelations, mean cause-specific survival probabilities of 88, 83 and 78% were determined at 10, 20 and 30 years, respectively. The survival-predicting software (PATHYPRE) written on the basis of the biostatistical model is available through Internet connections on the home page of the National Institute of Oncology, Budapest (www.oncol.hu).

CONCLUSION

Prediction of the individual survival probability for extrastudy cases affords a rationale for individualization of the treatment of papillary thyroid cancer patients.

[Volume changes to the neck lymph node metastases in head-neck tumors. The evaluation of radiotherapeutic treatment success]

AIM

This work is engaged with the volume change of neck lymph node metastasis of malignant tumors in the head-neck region during radiotherapy.

PATIENTS AND METHOD

In 54 patients with head and neck tumors, the volume of neck lymph nodes before and after radiation was measured. The volumetry was done with CT planimetry. The total dose was 66 Gy (2 Gy/d) telecobalt from 2 lateral opponated fields. The time of volume change could be defined with measuring of the half-time and the doubling-time by the help of Schwartz formula.

RESULTS

After 10 Gy the volume diminution was about 20% and half-time 24 to 26 days. Afterwards the time of volume diminution picked up speed and finally achieved 60 to 72%. Meanwhile the half-time decreased to the half value. The result was independent of the site of primary tumor, the patient's sex and age.

CONCLUSION

In our opinion the effectivity of radiotherapy can best be judged with defining of the volume change of lymph nodes of the neck.

Electromyographic analysis of muscle fatigue in anterior cruciate ligament deficient knees

The aim of this study was to detect possible differences in muscle fatigue and recovery of knee flexor and extensor muscles in patients with a deficient anterior cruciate ligament compared with patients with a normal anterior cruciate ligament. Surface electromyography of 15 patients with anterior cruciate ligament deficiency was performed while the muscles were under 80% of maximum isometric contraction, and after 1, 2, 3, and 5 minutes of rest. During the first 60 seconds of contraction, all muscles recorded significantly decreased mean power frequency and increased amplitude. The rate of decrease of mean power frequency was significantly greater in the injured quadriceps and normal hamstrings. All muscles except two recovered to the initial mean power frequency level after 1 minute of rest. All but two muscles in the injured and normal limb recorded an overshoot of mean power frequency during the recovery phase. This overshoot phenomenon also was seen for some muscles in the amplitude analysis. The findings confirm the fatigue state in all the muscles, suggest recruitment of more Type II fibers as the muscle fatigues, and show the physiologic adaptation of the quadriceps and hamstrings to anterior cruciate ligament insufficiency. The current study indirectly shows a dissociation between low intramuscular pH and mean power frequency during the recovery phase. It also indirectly suggests that the atrophied thigh muscles have fiber type composition similar to that of the normal side.

Inverse radiotherapy planning for a concave-convex PTV in cervical and upper mediastinal regions. Simulation of radiotherapy using an Alderson-RANDO phantom. Planning target volume

AIM

Three-dimensional inverse treatment planning with modulated beams was applied for dosimetric optimization of a lengthy (22 cm) and complex (concave-convex) shaped planning target volume (PTV) in the cervical and upper mediastinal regions.

MATERIAL AND METHOD

The planning was done for 9 coplanar beams spaced evenly at 40 intervals. Properties of 15 MV photons from a linear accelerator were simulated. The optimization of the fluence modulation profiles for each beam was based on a definition of the desired/permitted relative dose levels in the PTV and organs at risk, and a definition of the strengths of the constraints to achieve these objectives.

RESULTS

An adequate dose delivery to the PTV and protection of the spinal cord are completely achievable. The dose delivered to the lungs is clinically acceptable with respect to the risk of radiation-induced pneumonitis. For reasons of physics, no further decrease in the radiation burden on the lungs can be attained with X-rays without compromising the PTV coverage. The radiation burden on some critical part of normal tissues was effectively reduced by application of a dummy organ at risk.

CONCLUSION

The inverse planning is an effective method for conformal radiotherapy of large tumors as well. However, the power of the technique is insufficient when the tolerance dose of the neighbouring normal tissue is too low and its volume effect is high. Although requiring further operator interactions, introduction of dummy organs at risk may be of help in reducing the radiation burden on normal tissues.