Identification of interactions of binary variables associated with survival time using survivalFS.

Many medical studies aim to identify factors associated with a time to an event such as survival time or time to relapse. Often, in particular, when binary variables are considered in such studies, interactions of these variables might be the actual relevant factors for predicting, e.g., the time to recurrence of a disease. Testing all possible interactions is often not possible, so that procedures such as logic regression are required that avoid such an exhaustive search. In this article, we present an ensemble method based on logic regression that can cope with the instability of the regression models generated by logic regression. This procedure called survivalFS also provides measures for quantifying the importance of the interactions forming the logic regression models on the time to an event and for the assessment of the individual variables that take the multivariate data structure into account. In this context, we introduce a new performance measure, which is an adaptation of Harrel's concordance index. The performance of survivalFS and the proposed importance measures is evaluated in a simulation study as well as in an application to genotype data from a urinary bladder cancer study. Furthermore, we compare the performance of survivalFS and its importance measures for the individual variables with the variable importance measure used in random survival forests, a popular procedure for the analysis of survival data. These applications show that survivalFS is able to identify interactions associated with time to an event and to outperform random survival forests.

Cystatin C - a fast and reliable biomarker for glomerular filtration rate in head and neck cancer patients.

PURPOSE: Determination of renal function is a prerequisite for planning therapy in cancer patients. Limitations of creatinine as marker for the glomerular filtration rate (GFR) led to the proposal of cystatin C as a more accurate biomarker especially in mild renal insufficiency or in patients with low muscle mass. We compared the accuracy of cystatin C- and creatinine-based equations to estimate GFR in head and neck cancer (HNC) patients receiving platinum-based radiochemotherapy. PATIENTS AND METHODS: The study population consisted of 52 HNC patients (GFR range, 37-105 mL/min/1.73 m(2) complemented by 17 patients with known renal insufficiency (GFR range, 10-60 mL/min/1.73 m(2)). Intraclass correlation coefficients were calculated between the reference method (51)Cr-EDTA clearance and estimated GFR by creatinine clearance and equations based on creatinine (Cockroft-Gault, modification of diet in renal disease (MDRD), Wright) or cystatin C (Larsson, Dade-Behring, Hoek). In addition, sensitivity and specificity to discriminate GFR > 60 mL/min/1.73 m(2) were evaluated by receiver operating characteristic curve (ROC). RESULTS: The highest correlation coefficients were found for the cystatin C-based estimates in comparison with creatinine-based estimates or creatinine clearance, even though Bland-Altman plots revealed GFR overestimation for all equations tested. The cystatin C-based Hoek formula exhibited the highest overall precision and accuracy. GFR of < 60 mL/min/1.73 m(2) was assumed as a cut-off for chemotherapy. ROC analyses revealed the highest AUC to predict a GFR > 60 mL/min/1.73 m(2) for the creatinine-based Wright formula, closely followed by the MDRD formula and cystatin C-based equations of Larsson, Dade-Behring, and Hoek. CONCLUSION: Cystatin C-based GFR estimates showed the overall strongest correlation to the reference method. Thus, we recommend cystatin C for GFR estimation in HNC patients as an alternative method to the estimated creatinine clearance in clinical practice.

Echinococcus multilocularis: the impact of ionizing radiation on metacestodes.

Alveolar echinococcosis is caused by the metacestode stage of the fox tapeworm Echinococcus multilocularis. Current chemotherapeutical options for the treatment of echinococcosis are not satisfactory, and novel drugs and/or other potential means of therapy are needed. E. multilocularis metacestodes are characterized by almost potentially unlimited growth, and also display other features of cancerous tumours. In this study, we exposed metacestodes that were generated in vitro to 50-100 Gy ionizing irradiation, and subsequently investigated the short-term (10-12 days post-treatment) and long-term (14 weeks post-treatment) effects. We found, that in the short-term, no release of alkaline phosphatase (EmAP) activity as a measure for potentially induced damage and loss of viability could be detected, and that the protein expression pattern and protease activities in vesicle fluids and medium supernatants did not alter dramatically following irradiation. However, irradiation was associated with distinct morphological and ultrastructural alterations in the tissue of metacestodes, affecting most notably cell-cell contacts, mitochondrial shape, glycogen-storage cells and lipid droplet formation. These could be detected already at 10 days following treatment and remained as such also in the long-term. In addition, as determined after 14 weeks of culture, irradiation affected the proliferation and the growth of E. multilocularis metacestodes. Thus, we demonstrate that radiotherapy does not have a clear-cut parasitocidal effect, but can lead to metabolic impairment of E. multilocularis metacestodes, as reflected by the distinct morphological and structural alterations induced by irradiation treatment.

Randomized phase-III-trial of concurrent chemoradiation for locally advanced head and neck cancer comparing dose reduced radiotherapy with paclitaxel/cisplatin to standard radiotherapy with fluorouracil/cisplatin: The PacCis-trial.

BACKGROUND AND PURPOSE: This multicenter, phase 3 trial investigates whether the incorporation of concurrent paclitaxel and cisplatin together with a reduced total dose of radiotherapy is superior to standard fluorouracil-cisplatin based CRT. MATERIALS AND METHODS: Patients with SCCHN, stage III-IVB, were randomized to receive paclitaxel/cisplatin (PacCis)-CRT (arm A; paclitaxel 20 mg/m2 on days 2, 5, 8, 11 and 25, 30, 33, 36; cisplatin 20 mg/m2, days 1-4 and 29-32; RT to a total dose of 63.6 Gy) or fluorouracil/cisplatin (CisFU)-CRT (arm B; fluorouracil 600 mg/m2; cisplatin 20 mg/m2, days 1-5 and 29-33; RT: 70.6 Gy). Endpoint was 3-year-disease free survival (3y-DFS). RESULTS: A total of 221 patients were enrolled between 2010 and 2015. With a median follow-up of 3.7 years, 3y-DFS in the CisFU arm and PacCis arm was 58.2% and 48.4%, respectively (HR 0.82, 95% CI 0.56-1.21, p = 0.52). The 3y-OS amounted to 64.6% in the CisFU arm, and to 59.2% in the PacCis arm (HR 0.82, 95% CI 0.54-1.24, p = 0.43). In the subgroup of p16-positive oropharyngeal carcinomas, 3y-DFS and 3y-OS was 84.6% vs 83.9% (p = 0.653), and 92.3% vs. 83.5% (p = 0.76) in arm A and B, respectively. Grade 3-4 hematological toxicities were significantly reduced in arm A (anemia, p = 0.01; leukocytopenia, p = 0.003), whereas grade 3 infections were reduced in arm B (p = 0.01). CONCLUSION: Paclitaxel/cisplatin-CRT with a reduced RT-dose is not superior to standard fluorouracil/cisplatin-CRT. Subgroup analyses indicate that a reduced radiation dose seems to be sufficient for p16+ oropharyngeal cancer or non-smokers. CLINICAL TRIAL INFORMATION: NCT01126216; EudraCT Number 2005-003484-23.

Development and management of severe cutaneous side effects in head-and-neck cancer patients during concurrent radiotherapy and cetuximab.

BACKGROUND: The concurrent administration of cetuximab to radiotherapy has recently been shown to improve the clinical outcome of head-and-neck cancer (HNC) patients. An aggravation of the radiation-induced skin toxicity was not described. Here, however, two cases with severe skin toxicity during the combined treatment are reported. CLINICAL OBSERVATIONS: In a small group of five patients with locally advanced HNC treated with irradiation and concurrent cetuximab, two cases of unusually severe radiation dermatitis were observed. Both patients developed confluent moist desquamations confined to the irradiation field at a dose of 40 Gy (CTC [Common Toxicity Criteria] grade 3), which progressed into an ulcerative dermatitis (grade 4) at 58 Gy and 46 Gy, respectively. Histopathology showed a vacuolic degeneration of basal keratinocytes, subepidermal blister formation, and mixed perivascular and interstitial inflammatory infiltrates leading to a complete loss of the epidermis. These cutaneous side effects led to the discontinuation of radiotherapy. Topical corticosteroids and systemic antibiotic treatment resulted in wound healing, which allowed the continuation of radiotherapy. CONCLUSION: These findings indicate that cetuximab may have the potential to enhance the severity of radiation dermatitis in HNC patients. A systematic monitoring of cutaneous side effects during radiotherapy plus cetuximab is advised in order to reliably estimate the frequency of severe (grade 3/4) radiation dermatitis.

[Radiotherapy of soft tissue sarcoma--part of a multidisciplinary strategy]. / Radiotherapie der Weichteilsarkome--Teil einer multidisziplinären Strategie.

The management of soft tissue sarcoma has evolved from a solitary surgical treatment to an interdisciplinary multimodal approach including radiotherapy. These fundamental changes are the result of increased knowledge in tumor biology, radiation sensitivity and the improvement in modern radiation therapy techniques. A successful effective therapy regimen strongly depends on distinct preoperative diagnostics, preoperative conception of the surgical intervention and an experienced oncological team. Of significant importance for the prognosis is early diagnosis as well as tumor excision with a wide negative margin. However, even after complete wide resection in sano, the use of postoperative radiotherapy can further improve local control and should therefore be applied to the majority of patients. Consequently, radiotherapy should only be omitted in cases in which the tumor has been excised with a very wide negative margin; this implies, however, high quality of surgery and distinct histopathological analysis. Patients with non- or questionable resectable tumors, should be referred for pre-operative radiotherapy in order to improve the surgical results. Recent studies have underlined the efficiency of modern radiotherapy regimens. The different radiotherapy regimens will be highlighted against the background of tumor stage and tumor resectibility.

Accelerated vs. conventionally fractionated adjuvant radiotherapy in high-risk head and neck cancer: a meta-analysis.

BACKGROUND: Adjuvant radiotherapy in advanced head and neck squamous cell cancer (HNSCC) reduces the risk of local-regional failure and most likely increases the survival rate. Patients at high risk for tumor recurrence may benefit from more aggressive altered fractionation schedules in order to reduce the overall time from surgery to completion of radiotherapy. Here, we reviewed the results of six randomized trials addressing the above hypothesis. METHODS: In the six trials of interest, a total of 988 patients with locally advanced HNSCC were randomly assigned to receive either accelerated or conventionally fractionated adjuvant radiotherapy. Hazard ratios (HR) were extracted from available publications for local-regional control, distant metastasis as well as overall-, cancer specific- and disease-free survival. Meta-analysis of the effect sizes was performed using fixed and random effect models. Acute and late side effects were categorized and summarized for comparison. RESULTS: Accelerated radiotherapy did not improve the loco-regional control (n = 988, HR = 0.740, CI = 0.48-1.13, p = 0.162), progression-free survival (HR = 0.89, CI = 0.76-1.04, p = 0.132) or overall survival (HR = 0.88, CI = 0.75-1.04, p = 0.148) significantly. Acute confluent mucositis occurred with significant higher frequency with accelerated radiotherapy. Late side effects did not differ significantly in either group. CONCLUSION: Accelerated radiotherapy does not result in a significant improvement of loco-regional control or overall survival in high-risk patients. Acute but not late radiation toxicity were more frequent with the accelerated RT technique. In clinical practice accelerated postoperative radiation therapy might be a suitable option only for a subset of patients.

Induction chemotherapy followed by concurrent radio-chemotherapy versus concurrent radio-chemotherapy alone as treatment of locally advanced squamous cell carcinoma of the head and neck (HNSCC): A meta-analysis of randomized trials.

BACKGROUND: Induction chemotherapy with docetaxel, cisplatin and 5 FU (TPF) before radiotherapy (RT) or radio-chemotherapy (RT-CHX) has been shown to improve overall survival (OS) compared to induction chemotherapy with cisplatin and 5 FU in locally advanced squamous cell carcinoma of the head and neck (HNSCC). Whether TPF induction before RT-CHX improves clinical outcome in comparison with RT-CHX alone is still a matter of debate. Recently, the results of 5 randomized trials addressing this question have become available. METHODS: In the 5 trials of interest, in total 1022 patients with locally advanced HNSCC were randomly assigned to receive either TPF induction CHX followed by concurrent RT-CHX or concurrent RT-CHX alone. Platin or taxane based CHX was used during RT. 51.3% of the patients had oropharyngeal, 7.3% hypoharyngeal, 18.7% laryngeal, 19.4% oral cavity and 3.5% had other HNSCC. Published hazard ratios and hazard ratios extracted from available survival curves for OS and progression free survival (PFS) were basis of the meta-analysis. Meta-analysis of the effect sizes on OS and PFS was performed using a random effects model based on parameter estimates of log hazard ratios in Cox models and their standard errors. RESULTS: Additional induction CHX with TPF before RT-CHX did neither result in a significant improvement of OS (Hazard Ratio: 1.010, 95% confidence limits (CL) 0.84-1.21, p=0.92), nor in a statistically significant benefit of PFS (Hazard Ratio: 0.91, 95% CL 0.75-1.1, p=0.32). CONCLUSION: Additional induction CHX with TPF before RT-CHX does not improve OS and PFS in locally advanced HNSCC compared to definite RT-CHX.

Influence of dosimetric and clinical criteria on the requirement of artificial nutrition during radiotherapy of head and neck cancer patients.

PURPOSE/OBJECTIVE(S): Intensification of radiotherapy and chemotherapy for head-and-neck cancer (HNC) may lead to increased rates of long term dysphagia as a severe side effect. Mucositis and consequent swallowing problems require artificial nutrition in many HNC patients undergoing radiotherapy or chemoradiation. It is unknown, which predict factors for prophylactic PEG tube insertion appear useful. MATERIALS/METHODS: From an institutional database, 101 patients (72 male, 29 female, mean age 59.5years) were identified who underwent radiotherapy or chemoradiation for HNC. Primary end point of the investigation was the need for artificial nutrition for more than 4days during radiotherapy. Dose volume parameters of defined normal tissue structures potentially of relevance for swallowing ability as well as clinical factors were used to develop a predictive model using a binary multiple logistic regression model. RESULTS: Whereas several dosimetric and clinical factors were significant predictors for the need of artificial nutrition on univariate analysis, on multivariate analysis only three factors remained independently significant: mean dose to the oropharynx+1cm circumferential margin, ECOG performance state (0-1 vs. 2-4), and the use of chemotherapy (yes vs. no). CONCLUSIONS: Using a 3 parameter model we could distinguish HNC-patients with different risks for the need of artificial nutrition during radiotherapy. After independent validation, the model could be helpful to decision on prophylactic PEG tube insertion.

[Thymoma]. / Thymome.

Thymoma is a rare epithelial tumor of the thymus, but the most common malignancy in the anterior mediastinum. A unique feature is its association with paraneoplastic syndromes, in particular myasthenia gravis. According to the WHO classification 6 histologic types of thymic epithelial tumors can be discriminated. Tumor stage according to MASAOKA is the most important prognostic factor. Non-invasive tumors (stage I) are usually completely resected and no further therapy is warranted. For incompletely resected tumors and locally advanced invasive thymomas (stage Ill-IV) postoperative radiotherapy with 50-60 Gy is advisable. Chemotherapy, preferably with Cisplatinum, is indicated with inoperable thymomas or metastatic disease. In general thymomas have a fair prognosis even in advanced stage. Long term follow-up is mandatory up to 10 years.

Effects of Radiotherapy in the treatment of multiple myeloma: a retrospective analysis of a Single Institution.

BACKGROUND: Palliative irradiation of osteolytic lesions is a considerable component in the treatment for patients with multiple myeloma. In this study, we analyzed the efficacy of irradiation in these patients. PATIENTS AND METHODS: We retrospectively analyzed 153 patients with multiple myeloma who were admitted to our department between 1989 and 2013. According to the staging system of Durie & Salmon 116 patients were classified as stage III. 107/153 patients were treated with radiotherapy of at least one and up to 6 bony lesions at different times. In order to evaluate the effect of local radiotherapy on pain relief and bone recalcification a uni- and multivariate analysis was performed using a binary logistic regression model to correct for multiple measurements. Complete information on dose, fractionation and volume of radiotherapy was available from 81 patients treated in 136 target volumes for pain relief, and from 69 patients treated in 108 target volumes for recalcification. Total radiation doses varied between 8 Gy to 50 Gy (median dose 25 Gy in 2.5 Gy fractions, 5 times a week). RESULTS: Radiotherapy resulted in complete local pain relief in 31% and partial local pain relief in 54% of the patients. In the univariate analysis, higher total radiation doses (p = 0.023) and higher age (p = 0.014) at the time of radiotherapy were significantly associated with a higher likelihood of pain relief, whereas no significant association was detected for concurrent systemic treatment, type and stage of myeloma and location of bone lesions. The same variables were independent predictors for pain relief in the multivariate analysis. Recalcification was observed in 48% of irradiated bone lesions. In the uni- and multivariate analysis higher radiation doses were significantly associated (p = 0.048) with an increased likelihood of recalcification. Side effects of radiotherapy were generally mild. CONCLUSIONS: Higher total biological radiation doses were associated with better pain relief and recalcification in this retrospective evaluation of multiple myeloma patients. In addition, in the elderly the therapeutic measures appear to develop a better analgesic effect.

Radiotherapy in age-related macula degeneration.

PURPOSE: To ascertain the benefit from radiotherapy in age-related macula degeneration in a single-arm longitudinal study. METHODS AND MATERIALS: From 1997 to 1998, 39 patients with occult and 33 patients with classic choroidal neovascularization (CNV) were irradiated with 16 Gy. Fluorescein angiography and measurements of visual acuity were performed before and 3, 6, and 12 months after irradiation. RESULTS: Complete follow-up data for 1 year were available from 69 patients. The mean patient age was 72 years (range 49-92). Vision decreased in 43, was stable in 18, and improved in 8 cases. The mean vision deteriorated significantly (p = 0.02, Wilcoxon test), particularly within the first 3 months. Patients with occult CNV did significantly better than did those with classic CNV (p = 0.03). The proportion of patients retaining vision > or = 0.2 fell from 65% to 42% (p <0.01), for classic and occult CNV from 50% to 23%, and for occult CNV from 77% to 56% (p < 0.02), respectively. CNV size increased in 30 patients and was stable in 38. Neither age (p = 0.17) nor gender (p = 0.21, chi-square test) influenced prognosis. Four patients reported transitional complaints. CONCLUSION: Low-dose fractionated radiotherapy with 16 Gy is well tolerated. However, vision and reading ability were not preserved in most patients.

Coverage of anterior fossa in whole-brain irradiation.

PURPOSE: Whole-brain irradiation is indispensable in the treatment of several brain tumors and requires coverage of the entire subarachnoid space. Retrospective studies have revealed frequent recurrences in the frontobasal fossa above the cribriform plate (CP). We sought to determine how accurately the latter could actually be identified on lateral radiographs such as those used for radiotherapy planning. METHODS AND MATERIALS: The CP was localized by five radiation oncologists and five radiologists on lateral radiographs of 30 human skulls from an anatomic collection. Reference radiographs were acquired under identical conditions except for lead markers pointing to the CP and the ethmoid cells. The targeting accuracy was analyzed. RESULTS: In 39% (n = 116), the location of the CP was correctly estimated within 2 mm. Mislocations of 2-5, 5-10, and >10 mm were noted in 34% (n = 102), 20% (n = 61), and 7% (n = 21), respectively. Neither specialty nor experience (years of training) exerted a significant influence on targeting accuracy. If the roofs of the ethmoid cells formed prominent bony edges, they were mistaken for the CP in 37%. CONCLUSION: Lateral radiographs provide insufficient information to locate the CP accurately in whole brain irradiation. Additionally, localization was significantly impaired by prominent ethmoid cells.

Thymoma-a clinico-pathological long-term study with emphasis on histology and adjuvant radiotherapy dose.

INTRODUCTION: To evaluate prognostic factors of thymic epithelial tumors (TETs) with particular reference to histology and the dose-response relationship of adjuvant radiotherapy. METHODS: Retrospective study with central pathological review on patients resected for TET between 1966 and 2004 at a single institution. Prognostic factors were identified using Cox regression analysis. RESULTS: From 93 patients with TET, 33.3% relapsed and 47.3% died. Cause of death was known in 64% and attributed to TET in 25%. Myasthenia gravis was associated with superior disease-free survival (DFS) and overall survival (OS). Tumors smaller than 8.5 cm had a significantly better prognosis. With a median follow-up of 9.8 years actuarial OS at 5, 10, and 20 years were 96%, 92%, and 47% in stage I; 85%, 61%, and 53% in stage II; 72%, 39%, and 15% in stage III and IV. Advanced stage and incomplete resection had a negative impact on DFS and OS. According to histology (WHO type A, AB, B1; favorable; versus WHO type B2, B3; intermediate; versus thymic carcinoma, unfavorable) three prognostic groups were discernible. On multivariate analysis, tumor size, and stage emerged as prognostic factors, but neither histology nor myasthenia. Postoperative radiotherapy was administered in 27 patients (median dose 50.8 Gy). Doses in excess of 50 Gy were associated with significantly improved DFS and OS. CONCLUSIONS: Tumor stage, histology, complete resection, and tumor size had a significant impact on survival. Myasthenia may facilitate early detection and is correlated with superior survival. When postoperative radiotherapy is administered, doses above 50 Gy may improve outcome.

Palliative radiotherapy tailored to life expectancy in end-stage cancer patients: reality or myth?

BACKGROUND: The purpose of the study was to investigate the adequacy of palliative radiation treatment in end-stage cancer patients. METHODS: Of 216 patients referred for palliative radiotherapy, 33 died within 30 days and constitute the population of the study. Symptoms, Karnofsky Performance Status (KPS), laboratory tests, and survival estimates were obtained. Treatment course was evaluated by medical records. Univariate analyses were performed by using the 2-sided chi-square test. With significant variables, multiple regression analysis was performed. RESULTS: Median age was 65 years, and median survival was 15 days. Prevailing primary cancer types were lung (39%) and breast (18%). Metastases were present in 94% of patients, brain (36%), bone (24%) and lung (18%). In 91%, KPS was < 0%. KPS, lactate dehydrogenase, dyspnea, leucocytosis, and brain metastases conveyed a poor prognosis. From 85 survival estimates, only 16% were correct, but 21% expected more than 6 months. Radiotherapy was delivered to 91% of patients. In 90% of radiation treatments, regimens of at least 30 Gy with fractions of 2-3 Gy were applied. Half of the patients spent greater than 60% of their remaining lifespan on therapy. In only 58% of patients was radiotherapy completed. Progressive complaints were noted in 52% and palliation in 26%. CONCLUSIONS: Radiotherapy was not appropriately customized to these patients considering the median treatment time, which resembles the median survival time. About half of the patients did not benefit despite spending most of their remaining lives on therapy. Prolonged irradiation schedules probably reflect overly optimistic prognoses and unrealistic concerns about late radiation damage. Single-fraction radiotherapy was too seldom used.

Leser-Trélat sign presenting in a patient with ovarian cancer: a case report.

INTRODUCTION: Seborrheic keratoses are very common findings in elderly patients. However, a sudden onset and dramatic increase in the number and size of these benign lesions deserves special attention, since this may represent the Leser Trélat sign, a rare paraneoplastic cutaneous syndrome. CASE PRESENTATION: A 92-year-old female presented to our clinic with multiple eruptive seborrheic keratoses, which had dramatically increased in size and number over the past two years. A diagnostic work-up revealed an ovarian carcinoma. Hence, cutaneous findings in our patient were consistent with the diagnosis of the Leser-Trélat sign. CONCLUSION: The Leser-Trélat sign may coincide with the diagnosis of occult cancer or follow or precede it by months or years. Practitioners should take cases of eruptive seborrheic keratoses seriously and perform thorough patient examinations.

PSA after incidental irradiation of the nonmalignant prostate: long-term changes.

BACKGROUND: Incidental irradiation of the prostate may affect serum prostate-specific antigen (PSA). However, scarce data exist on PSA changes after irradiation of noncancerous prostatic tissue. This is an update of a study on PSA after pelvic irradiation. MATERIAL AND METHODS: From 1997 to 2007, blood samples of 33 men were examined who had undergone pelvic irradiation for rectal or anal cancer. The planning target volume included the prostate in all cases. No patient had clinical evidence of prostatic disease. Radiotherapy was applied in fractions of 1.8-2 Gy up to 40-50 Gy (n = 3), 50-60 Gy (n = 21), and 60-65 Gy (n = 2). Seven patients received 5 x 5 Gy. Serum PSA was measured before, during, and after radiotherapy periodically. Median log (PSA) changes were calculated according to elapsed time from starting radiotherapy. The significance was tested with chi(2)-test. RESULTS: 18 patients died during follow-up. For 15 patients, long-term PSA data with a median follow-up of 9 years (2,546-3,528 days) are available. PSA levels rose during the first weeks of irradiation peaking at 2-4 weeks with a significant 2.7-fold increase (p < 0.01). 1 year after radiation therapy, PSA declined below (90%) the preirradiation level, but this difference was not significant (p = 0.36). On further follow-up PSA did not change up to 8.9 years after radiotherapy (p = 0.36). CONCLUSION: Irradiation of the prostate causes transient increase of serum PSA. By 1 year, PSA has returned near the preirradiation value and stays there for at least 9 years. A major interference with prostate cancer screening or surveillance after radiotherapy is therefore unlikely.