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Delineation of gross tumor volume (GTV) for radiation treatment planning of locally advanced rectal cancer using information from MRI or FDG-PET/CT: a prospective study
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Oncology.
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2011 (English)In: International Journal of Radiation Oncology, Biology, Physics, ISSN 0360-3016, Vol. 81, no 4, e439-e445 p.Article in journal (Refereed) Published
Abstract [en]


Accurate delineation of target volumes is important to maximize radiation dose to the tumor and minimize it to nontumor tissue. Computed tomography (CT) and magnetic resonance imaging (MRI) are standard imaging modalities in rectal cancer. The aim was to explore whether functional imaging with F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET), combined with CT (FDG-PET/CT) gives additional information to standard pretreatment evaluation and changes the shape and size of the gross tumor volume (GTV).


From 2007 to 2009, 77 consecutive patients with locally advanced rectal cancer were prospectively screened for inclusion in the study at two university hospitals in Sweden, and 68 patients were eligible. Standard GTV was delineated using information from clinical examination, CT, and MRI (GTV-MRI). Thereafter, a GTV-PET was defined in the fused PET-CT, and the target volume delineations were compared for total volume, overlap, and mismatch. Pathologic uptake suspect of metastases was also registered.


The median volume of GTV-MRI was larger than that of GTV-PET: 111 cm3 vs. 87 cm3 (p < 0.001). In many cases, the GTV-MRI contained the GTV defined on the PET/CT images as subvolumes, but when a GTV total was calculated after the addition of GTV-PET to GTV-MRI, the volume increased, with median 11% (range, 0.5–72%). New lesions were seen in 15% of the patients for whom PET/CT was used.


FDG-PET/CT facilitates and adds important information to the standard delineation procedure of locally advanced rectal cancer, mostly resulting in a smaller GTV, but a larger total GTV using the union of GTV-MRI and GTV-PET. New lesions were sometimes seen, potentially changing the treatment strategy.

Place, publisher, year, edition, pages
2011. Vol. 81, no 4, e439-e445 p.
National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-169858DOI: 10.1016/j.ijrobp.2011.03.031ISI: 000309412300031PubMedID: 21641122OAI: oai:DiVA.org:uu-169858DiVA: diva2:507857
Available from: 2012-03-06 Created: 2012-03-06 Last updated: 2012-11-07Bibliographically approved
In thesis
1. Optimising Radiotherapy in Rectal Cancer Patients
Open this publication in new window or tab >>Optimising Radiotherapy in Rectal Cancer Patients
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Rectal cancer is the eight most common cancer diagnosis in Sweden in both men and women, with almost 2000 new cases per year. Radiotherapy, which is an important treatment modality for rectal cancer, has evolved during the past decades. Diagnostic tools have also improved, allowing better staging and offering information used to make well-founded decisions in multidisciplinary team conferences.

In a retrospective study (n=46) with locally advanced rectal cancer (LARC) patients, unfit for chemoradiotherapy, patients were treated with short-course radiotherapy. Delayed surgery was done when possible. Radical surgery was possible in 89% of the patients who underwent surgery (80%). Grade IV diarrhoea affected three elderly patients. Target radiation volume should be reduced in elderly or metastatic patients.

In a prospective study (n=68) with LARC patients, magnetic resonance imaging (MRI) and 2-18F-fluoro-2-D-deoxyglucose (FDG) positron emission tomography (PET) were used to determine if FDG-PET could provide extra treatment information. Information from FDG-PET changed the stage of 10 patients. Delineation with FDG-PET generally resulted in smaller target volumes than MRI only.

Seven of the most advanced LARC patients in the above cohort were used for a methodological study to determine if dose escalation to peripheral, non-resectable regions was feasible. Simultaneous integrated boost plans with photons and protons were evaluated. While toxicity was acceptable in five patients with both protons and photons, two patients with very large tumours had unacceptable risk for intestinal toxicity regardless of modality.

In the interim analysis of the Stockholm III Trial (n=303, studying radiotherapy-fractionation and timing of surgery in relation to radiotherapy) compliance was acceptable and severe acute toxicity was infrequent, irrespective of fractionation. Short-course radiotherapy with immediate surgery tended to give more postoperative complications, but only if surgery was delayed more than 10 days after the start of radiotherapy.

Quality-of-life in the Stockholm III Trial was studied before, during and shortly after treatment using the EORTC QLQ-C30 and CR38 questionnaires. Surgery accounted for more adverse effects than radiotherapy in all groups. Postoperatively, the poorest quality-of-life was seen in patients given short-course radiotherapy followed by immediate surgery. No postoperative differences were seen between the two groups with delayed surgery.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. 57 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 775
Rectal cancer, locally advanced, radiotherapy, FDG-PET, peripheral boost, protons, quality-of-life
National Category
Cancer and Oncology
Research subject
urn:nbn:se:uu:diva-172531 (URN)978-91-554-8367-8 (ISBN)
Public defence
2012-06-11, Skoogsalen, Akademiska Sjukhuset, ingång 78, Uppsala, 13:15 (Swedish)
Available from: 2012-05-21 Created: 2012-04-11 Last updated: 2012-08-01Bibliographically approved

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