Peter Meidahl Petersen

IT University of Copenhagen, København, Capital Region, Denmark

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Publications (75)285.58 Total impact

  • International journal of radiation oncology, biology, physics 11/2015; 93(3):E458-E459. DOI:10.1016/j.ijrobp.2015.07.1717 · 4.26 Impact Factor
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    ABSTRACT: Background: The purpose of this observational cohort study was to evaluate the outcome and prognostic factors following salvage radiotherapy (SRT) in a consecutive national cohort. Material and methods: Between 2006 and 2010, 259 patients received SRT in Denmark. Patient- and cancer-related characteristics were retrospectively retrieved from patient charts. The primary end point was biochemical progression-free survival (b-PFS). Results: At the end of follow-up, 51% of the patients displayed a prostate-specific antigen (PSA) level <0.1 ng/ml. The three-year b-PFS rate for the total cohort was 57.0%. Nearly half of the patients (44%) received androgen deprivation therapy (ADT) in combination with SRT. Positive surgical tumour margins (p = 0.025) and ADT (p = 0.001) were the only markers independently correlated with b-PFS. In patients who received SRT without ADT, both a pre-SRT PSA level ≤0.5 ng/ml (p = 0.003) and pathological tumour stage T1-T2 (p = 0.036) independently correlated with b-PFS. Moreover, a duration between radical prostatectomy (RP) and SRT ≤29 months (p = 0.035) independently correlated with b-PFS in patients treated with ADT in combination with RT. Conclusions: In patients treated for biochemical failure after RP, positive surgical tumour margins and PSA levels ≤0.5 ng/mL at the time of SRT were associated with a favourable outcome. Despite less favourable tumour characteristics, patients receiving SRT and ADT demonstrated improved b-PFS, and in particular, patients with PSA levels >0.2 ng/ml benefitted from additional ADT.
    Acta oncologica (Stockholm, Sweden) 09/2015; DOI:10.3109/0284186X.2015.1088170 · 3.00 Impact Factor
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    Maria R Kamstrup · Robert Gniadecki · Lars Iversen · Lone Skov · Peter Meidahl Petersen · Annika Loft · Lena Specht ·
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    ABSTRACT: Cutaneous T-cell lymphomas (CTCLs) are dominated by mycosis fungoides (MF) and Sézary syndrome (SS), and durable disease control is a therapeutic challenge. Standard total skin electron beam therapy (TSEBT) is an effective skin-directed therapy, but the possibility of retreatments is limited to 2 to 3 courses in a lifetime due to skin toxicity. This study aimed to determine the clinical effect of low-dose TSEBT in patients with MF and SS. In an open clinical study, 21 patients with MF/SS stages IB to IV were treated with low-dose TSEBT over <2.5 weeks, receiving a total dose of 10 Gy in 10 fractions. Data from 10 of these patients were published previously but were included in the current pooled data analysis. Outcome measures were response rate, duration of response, and toxicity. The overall response rate was 95% with a complete cutaneous response or a very good partial response rate (<1% skin involvement with patches or plaques) documented in 57% of the patients. Median duration of overall cutaneous response was 174 days (5.8 months; range: 60-675 days). TSEBT-related acute adverse events (grade 1 or 2) were observed in 60% of patients. Low-dose (10-Gy) TSEBT offers a high overall response rate and is relatively safe. With this approach, reirradiation at times of relapse or progression is likely to be less toxic than standard dose TSEBT. It remains to be established whether adjuvant and combination treatments can prolong the beneficial effects of low-dose TSEBT. Copyright © 2015 Elsevier Inc. All rights reserved.
    International journal of radiation oncology, biology, physics 05/2015; 92(1):138-143. DOI:10.1016/j.ijrobp.2015.01.047 · 4.26 Impact Factor
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    ABSTRACT: Hodgkin lymphoma (HL) survivors have an increased risk of cardiovascular disease (CD), lung cancer, and breast cancer. We investigated the risk for the development of CD and secondary lung, breast, and thyroid cancer after radiation therapy (RT) delivered with deep inspiration breath-hold (DIBH) compared with free-breathing (FB) using 3-dimensional conformal RT (3DCRT) and intensity modulated RT (IMRT). The aim of this study was to determine which treatment modality best reduced the combined risk of life-threatening late effects in patients with mediastinal HL. Twenty-two patients with early-stage mediastinal HL were eligible for the study. Treatment plans were calculated with both 3DCRT and IMRT on both DIBH and FB planning computed tomographic scans. We reported the estimated dose to the heart, lung, female breasts, and thyroid and calculated the estimated life years lost attributable to CD and to lung, breast, and thyroid cancer. DIBH lowered the estimated dose to heart and lung regardless of delivery technique (P<.001). There was no significant difference between IMRT-FB and 3DCRT-DIBH in mean heart dose, heart V20Gy, and lung V20Gy. The mean breast dose was increased with IMRT regardless of breathing technique. Life years lost was lowest with DIBH and highest with FB. In this cohort, 3DCRT-DIBH resulted in lower estimated doses and lower lifetime excess risks than did IMRT-FB. Combining IMRT and DIBH could be beneficial for a subgroup of patients. Copyright © 2015 Elsevier Inc. All rights reserved.
    International journal of radiation oncology, biology, physics 03/2015; 92(1). DOI:10.1016/j.ijrobp.2015.01.013 · 4.26 Impact Factor
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    ABSTRACT: Early-stage Hodgkin lymphoma (HL) is a rare disease, and the location of lymphoma varies considerably between patients. Here, we evaluate the variability of radiation therapy (RT) plans among 5 International Lymphoma Radiation Oncology Group (ILROG) centers with regard to beam arrangements, planning parameters, and estimated doses to the critical organs at risk (OARs). Ten patients with stage I-II classic HL with masses of different sizes and locations were selected. On the basis of the clinical information, 5 ILROG centers were asked to create RT plans to a prescribed dose of 30.6 Gy. A postchemotherapy computed tomography scan with precontoured clinical target volume (CTV) and OARs was provided for each patient. The treatment technique and planning methods were chosen according to each center's best practice in 2013. Seven patients had mediastinal disease, 2 had axillary disease, and 1 had disease in the neck only. The median age at diagnosis was 34 years (range, 21-74 years), and 5 patients were male. Of the resulting 50 treatment plans, 15 were planned with volumetric modulated arc therapy (1-4 arcs), 16 with intensity modulated RT (3-9 fields), and 19 with 3-dimensional conformal RT (2-4 fields). The variations in CTV-to-planning target volume margins (5-15 mm), maximum tolerated dose (31.4-40 Gy), and plan conformity (conformity index 0-3.6) were significant. However, estimated doses to OARs were comparable between centers for each patient. RT planning for HL is challenging because of the heterogeneity in size and location of disease and, additionally, to the variation in choice of treatment techniques and field arrangements. Adopting ILROG guidelines and implementing universal dose objectives could further standardize treatment techniques and contribute to lowering the dose to the surrounding OARs. Copyright © 2015 Elsevier Inc. All rights reserved.
    International journal of radiation oncology, biology, physics 02/2015; 92(1). DOI:10.1016/j.ijrobp.2014.12.009 · 4.26 Impact Factor
  • Peter M. Petersen · Karina Seierøe · Bente Pakkenberg ·
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    ABSTRACT: The aim of this study was to estimate the total number of Sertoli and Leydig cells in testes from male subjects across the human lifespan, using an optimized stereological method for cell-counting. In comparison with many other organs, estimation of the total cell numbers in the testes is particularly sensitive to methodological problems. Therefore, using the optical fractionator technique and a sampling design specifically optimized for human testes, we estimated the total number of Sertoli and Leydig cells in the testes from 26 post mortem male subjects ranging in age from 16 to 80 years. The mean unilateral total number of Sertoli cells was 407 × 106 [range: 86 × 106 to 665 × 106, coefficient of variation (CV) = 0.33], and the mean unilateral total number of Leydig cells was 99 × 106 (range: 47 × 106 to 245 × 106, CV = 0.48). There was a significant decline in the number of Sertoli cells with age; no such decline was found for Leydig cells. Quantitative stereological analysis of post mortem tissue may help understand the influence of age or disease on the number of human testicular cells.
    Journal of Anatomy 12/2014; 226(2). DOI:10.1111/joa.12261 · 2.10 Impact Factor
  • M. Hojgaard · M.C. Aznar · D.A. Schut · L. Specht · A.N. Pedersen · P.M. Petersen ·

    International journal of radiation oncology, biology, physics 09/2014; 90(1):S834-S835. DOI:10.1016/j.ijrobp.2014.05.2398 · 4.26 Impact Factor

  • International journal of radiation oncology, biology, physics 09/2014; 90(1):S405-S406. DOI:10.1016/j.ijrobp.2014.05.1291 · 4.26 Impact Factor
  • M.C. Aznar · M.V. Maraldo · A.K. Berthelsen · D.A. Schut · A. Loft · L. Specht · P.M. Petersen ·

    International journal of radiation oncology, biology, physics 09/2014; 90(1):S673. DOI:10.1016/j.ijrobp.2014.05.1980 · 4.26 Impact Factor
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    ABSTRACT: Background: Long-term Hodgkin lymphoma (HL) survivors have an increased risk of late cardiac morbidity and secondary lung cancer after chemotherapy and mediastinal radiotherapy. In this prospective study we investigate whether radiotherapy with deep inspiration breath-hold (DIBH) can reduce radiation doses to the lungs, heart, and cardiac structures without compromising the target dose. Patients and methods: Twenty-two patients (14 female, 8 male), median age 30 years (18-65 years), with supra-diaphragmatic HL were enrolled and had a thoracic PET/CT with DIBH in addition to staging FDG-PET/CT in free breathing (FB) and a planning CT in both FB and DIBH. For each patient an involved-node radiotherapy plan was done for both DIBH and FB, and the doses to the lungs, heart, and female breasts were recorded prospectively. Mean doses to the heart valves and coronary arteries were recorded retrospectively. Patients were treated with the technique yielding the lowest doses to normal structures. Results: Nineteen patients were treated with DIBH and three with FB. DIBH reduced the mean estimated lung dose by 2.0 Gy (median: 8.5 Gy vs. 7.2 Gy) (p < 0.01) and the mean heart dose by 1.4 Gy (6.0 Gy vs. 3.9 Gy) (p < 0.01) compared to FB. The lung and heart V20Gy were reduced with a median of 5.3% and 6.3%. Mean doses to the female breasts were equal with FB and DIBH. Conclusion: DIBH can significantly decrease the estimated mean doses to the heart and lungs without lowering the dose to the target in radiotherapy for patients with mediastinal HL.
    Acta oncologica (Stockholm, Sweden) 07/2014; 54(1):1-7. DOI:10.3109/0284186X.2014.932435 · 3.00 Impact Factor
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    ABSTRACT: Objective: The aim of this study was to prospectively assess the development of 24 urinary, gastrointestinal and sexual symptoms in patients with prostate cancer (PCa) during and after image-guided volumetric modulated arc therapy (IG-VMAT). Material and methods: A total of 87 patients with PCa participated in this study. The patients were asked to complete a modified version of the Prostate Cancer Symptom Scale (PCSS) questionnaire before radiotherapy (RT) (baseline), at the start of RT, at the end of RT and 1 year after RT. Changes in symptoms at the start of RT, at the end of RT and 1 year after RT compared to baseline were analysed by a mixed model analysis of repeated measurements with the following covariates: age, comorbidity, smoking and androgen deprivation therapy (ADT). Results: All urinary problems except for haematuria increased significantly at the end of RT compared to baseline. One year after RT, there was no longer any difference compared to baseline for any of the urinary symptoms. All gastrointestinal symptoms except for nausea increased significantly at the end of RT. One year after RT, patients also reported slightly higher degrees of stool frequency, bowel leakage, planning of toilet visits, flatulence, mucus, gastrointestinal bleeding and impact of gastrointestinal bother on daily activities compared to baseline. All sexual symptoms increased significantly at all times compared to baseline. The use of ADT was associated with worse sexual symptoms. Conclusions: IG-VMAT is a safe treatment for PCa, with few and mild changes in urinary and gastrointestinal symptoms 1 year after RT compared to baseline. Sexual symptoms deteriorated both during and after RT. The use of ADT was associated with worse sexual symptoms.
    Scandinavian Journal of Urology 05/2014; 49(1). DOI:10.3109/21681805.2014.913258 · 1.25 Impact Factor
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    ABSTRACT: The use of radiotherapy (RT) is debated for pediatric patients with Hodgkin lymphoma (HL) due to the late effects of treatment. Radiation doses to the thyroid, heart, lungs, and breasts are compared with the extensive mantle field (MF), Involved Field RT(IFRT), Modified IFRT (mIFRT), and Involved Node RT (INRT) and the risk of radiation-induced cardiovascular disease, secondary cancers, and the corresponding Life Years Lost (LYL) is estimated with each technique. INRT, mIFRT, IFRT, and MF plans (20 and 30 Gy) were simulated for 10 supradiaphragmatic, clinical stage I–II classical HL patients <18 years old, total of 4 x 2 plans for each patient. The lifetime excess risks of cardiac morbidity, cardiac mortality, lung, breast, and thyroid cancer with each technique were estimated. The estimated excess risks attributable to RT were based on HL series with long-term follow-up, treating death from other causes as competing risks. The corresponding LYL were derived from the estimated excess risks. Statistical analyses were performed with repeated measures ANOVA. Both a reduction in field size and in prescribed radiation dose significantly lowered the estimated dose to the heart, lungs, breasts, and thyroid compared to past,extended fields, even for patients with mediastinal disease. This translated into a significantly reduced estimated risk of cardiovascular disease, secondary cancers, and LYL. Involved Node Radiotherapy should be considered for pediatric patients with Hodgkin lymphoma since it is estimated to substantially lower the risk of severe long-term complications.
    Pediatric Blood & Cancer 04/2014; 61(4):717-22. DOI:10.1002/pbc.24861 · 2.39 Impact Factor
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    ABSTRACT: Image-guided radiotherapy (IGRT) facilitates the delivery of a very precise radiation dose. In this study we compare the toxicity and biochemical progression-free survival between patients treated with daily image-guided intensity-modulated radiotherapy (IG-IMRT) and 3D conformal radiotherapy (3DCRT) without daily image guidance for high risk prostate cancer (PCa). A total of 503 high risk PCa patients treated with radiotherapy (RT) and endocrine treatment between 2000 and 2010 were retrospectively reviewed. 115 patients were treated with 3DCRT, and 388 patients were treated with IG-IMRT. 3DCRT patients were treated to 76 Gy and without daily image guidance and with 1-2 cm PTV margins. IG-IMRT patients were treated to 78 Gy based on daily image guidance of fiducial markers, and the PTV margins were 5-7 mm. Furthermore, the dose-volume constraints to both the rectum and bladder were changed with the introduction of IG-IMRT. The 2-year actuarial likelihood of developing grade > = 2 GI toxicity following RT was 57.3% in 3DCRT patients and 5.8% in IG-IMRT patients (p < 0.001). For GU toxicity the numbers were 41.8% and 29.7%, respectively (p = 0.011). On multivariate analysis, 3DCRT was associated with a significantly increased risk of developing grade > = 2 GI toxicity compared to IG-IMRT (p < 0.001, HR = 11.59 [CI: 6.67-20.14]). 3DCRT was also associated with an increased risk of developing GU toxicity compared to IG-IMRT. The 3-year actuarial biochemical progression-free survival probability was 86.0% for 3DCRT and 90.3% for IG-IMRT (p = 0.386). On multivariate analysis there was no difference in biochemical progression-free survival between 3DCRT and IG-IMRT. The difference in toxicity can be attributed to the combination of the IMRT technique with reduced dose to organs-at-risk, daily image guidance and margin reduction.
    Radiation Oncology 02/2014; 9(1):44. DOI:10.1186/1748-717X-9-44 · 2.55 Impact Factor
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    ABSTRACT: To present a novel tool that allows quantitative estimation and visualization of the risk of various relevant normal tissue endpoints to aid in treatment plan comparison and clinical decision making in radiation therapy (RT) planning for Hodgkin lymphoma (HL). A decision-support tool for risk-based, individualized treatment plan comparison is presented. The tool displays dose-response relationships, derived from published clinical data, for a number of relevant side effects and thereby provides direct visualization of the trade-off between these endpoints. The Quantitative Analyses of Normal Tissue Effects in the Clinic reports were applied, complemented with newer data where available. A "relevance score" was assigned to each data source, reflecting how relevant the input data are to current RT for HL. The tool is applied to visualize the local steepness of dose-response curves to drive the reoptimization of a volumetric modulated arc therapy treatment plan for an HL patient with head-and-neck involvement. We also use this decision-support tool to visualize and quantitatively evaluate the trade-off between a 3-dimensional conformal RT plan and a volumetric modulated arc therapy plan for a patient with mediastinal HL. This multiple-endpoint decision-support tool provides quantitative risk estimates to supplement the clinical judgment of the radiation oncologist when comparing different RT options.
    International journal of radiation oncology, biology, physics 12/2013; 88(2). DOI:10.1016/j.ijrobp.2013.10.028 · 4.26 Impact Factor
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    ABSTRACT: To evaluate dose plans for head and neck organs at risk (OARs) for classical Hodgkin lymphoma (HL) patients using involved node radiotherapy (INRT) delivered as 3D conformal radiotherapy (3DCRT), volumetric modulated arc therapy (VMAT), and intensity modulated proton therapy (PT), in comparison to the past mantle field (MF). Data from 37 patients with cervical lymph node involvement were used. All patients originally received chemotherapy followed by 3DCRT-INRT (30.6Gy). A VMAT-INRT, PT-INRT (both 30.6Gy), and a MF plan (36Gy) were simulated. Doses to head and neck OARs were compared with cumulative DVHs and repeated measures ANOVA. The estimated median mean doses were 15.3, 19.3, 15.4, and 37.3Gy (thyroid), 10.9, 12.0, 7.9, and 34.5Gy (neck muscles), 2.3, 11.1, 1.8, and 37.1Gy (larynx), 1.7, 5.1, 1.3, and 23.8Gy (pharynx), 0.5, 0.8, 0.01, and 32.3Gy (ipsilateral parotid), and 2.4, 3.8, 0.7, and 34.7Gy (ipsilateral submandibular) with 3DCRT, VMAT, PT, and MF (all p<0.0001), respectively. The use of INRT significantly lowered the estimated radiation dose to the head and neck OARs. VMAT appeared suboptimal compared to 3DCRT and PT, and for some patients, PT offered an additional gain.
    Radiotherapy and Oncology 11/2013; 110(3). DOI:10.1016/j.radonc.2013.09.027 · 4.36 Impact Factor
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    ABSTRACT: Introduction: The cure rate of early stage Hodgkin's lymphoma (HL) is excellent; investigating the late effects of treatment is thus important. Esophageal toxicity is a known side effect in patients receiving radiotherapy (RT) to the mediastinum, although little is known of this in HL survivors. This study investigates the dose to the esophagus in the treatment of early stage HL using different RT techniques. Estimated risks of early esophagitis, esophageal stricture and cancer are compared between treatments. Material and methods: We included 46 patients ≥ 15 years with supradiaphragmatic, clinical stage I-II HL, who received chemotherapy followed by involved node RT (INRT) to 30.6 Gy at our institution. INRT was planned with three-dimensional conformal RT (3DCRT). For each patient a volumetric modulated arc therapy (VMAT), proton therapy (PT) and mantle field (MF) treatment plan was simulated. Mean, maximum and minimum dose to the esophagus were extracted from the treatment plans. Risk estimates were based on dose-response models from clinical series with long-term follow-up. Statistical analyses were performed with repeated measures ANOVA using Bonferroni corrections. Results: Mean dose to the esophagus was 16.4, 16.4, 14.7 and 34.2 Gy (p < 0.001) with 3DCRT, VMAT, PT and MF treatment, respectively. No differences were seen in the estimated risk of developing esophagitis, stricture or cancer with 3DCRT compared to VMAT (p = 1.000, p = 1.000, p = 0.356). PT performed significantly better with the lowest risk estimates on all parameters compared to the photon treatments, except compared to 3DCRT for stricture (p = 0.066). On all parameters the modern techniques were superior to MF treatment (p < 0.001). Conclusions: The estimated dose to the esophagus and the corresponding estimated risks of esophageal complications are decreased significantly with highly conformal RT compared to MF treatment. The number of patients presenting with late esophageal side effects will, thus, likely be minimal in the future.
    Acta oncologica (Stockholm, Sweden) 10/2013; 52(7):1559-65. DOI:10.3109/0284186X.2013.813636 · 3.00 Impact Factor

  • International Journal of Radiation OncologyBiologyPhysics 10/2013; 87(2):S62. DOI:10.1016/j.ijrobp.2013.06.162 · 4.26 Impact Factor

  • International Journal of Radiation OncologyBiologyPhysics 10/2013; 87(2):S348-S349. DOI:10.1016/j.ijrobp.2013.06.915 · 4.26 Impact Factor

  • International Journal of Radiation OncologyBiologyPhysics 10/2013; 87(2):S599-S600. DOI:10.1016/j.ijrobp.2013.06.1587 · 4.26 Impact Factor

Publication Stats

1k Citations
285.58 Total Impact Points


  • 2011-2015
    • IT University of Copenhagen
      København, Capital Region, Denmark
    • University of North Carolina at Chapel Hill
      North Carolina, United States
  • 2003-2014
    • Rigshospitalet
      • Department of Oncology
      København, Capital Region, Denmark
  • 2013
    • Aarhus University
      • Department of Clinical Medicine
      Aarhus, Central Jutland, Denmark
    • Albert Einstein College of Medicine
      • Department of Radiation Oncology
      New York City, New York, United States
  • 2012-2013
    • Region Hovedstaden
      Hillerød, Capital Region, Denmark
  • 1998-2012
    • Copenhagen University Hospital
      København, Capital Region, Denmark
  • 2002
    • Aarhus University Hospital
      Aarhus, Central Jutland, Denmark
  • 2000
    • University of Copenhagen Herlev Hospital
      Herlev, Capital Region, Denmark
  • 1999
    • Herlev Hospital
      Herlev, Capital Region, Denmark
  • 1997
    • National University (California)
      San Diego, California, United States