Has PET/CT a role in the characterization of indeterminate lung lesions on staging CT in colorectal cancer? A prospective study.
OBJECTIVE
CT has been found superior to chest x-ray to detect lung malignances. However, indeterminate lung lesions (ILL) are found in 4-42% by using CT in staging colorectal cancer (CRC) patients. Our aim was to examine the frequency of ILL on staging CT and the rate of the ILL being malignant, and to investigate if PET/CT was useful in pointing out the malignant cases.


METHODS
A prospective analysis of 238 consecutive patients operated for CRC followed median 24 months. All the patients had a preoperative staging CT. Patients with ILL had a PET/CT scan performed 3 months postoperatively and low dose chest CT performed 6, 12, 18 and 24 months postoperatively.


RESULTS
Twenty percent of the patients had ILL. Four of these patients (8.5%) had lung metastases detected median 9 months postoperatively, while 2 (4.3%) had other lung malignancies. One patient had TB. In patients with normal staging chest CT 10 of the 185 patients (5.4%) developed lung metastases detected median 16 months postoperatively. This was significantly later than in patients with ILL (p < 0.001), but with regard to the number of patients developing lung metastases no significant difference was found between the groups (p = 0.12).


CONCLUSIONS
Even though a relative low number of ILL turn out to be malignant it seems advisable to use PET/CT scan in the follow-up to detect lung metastases as early as possible to better the prognosis. For the same reason all CRC patients should have chest CT included in their follow-up 6-12 months postoperatively.
Department of Surgery, Roskilde University Hospital, Denmark; Faculty of Health Sciences, University of Copenhagen, Denmark. Electronic address: pjss@regionsjaelland.dk.
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P
Jess
Department of Surgery, Roskilde University Hospital, Denmark; Faculty of Health Sciences, University of Copenhagen, Denmark.
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Seiersen
Department of Surgery, Roskilde University Hospital, Denmark.
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H
Ovesen
Department of Radiology, Roskilde University Hospital, Denmark.
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H
Sandstrøm
Department of Lung Diseases, Roskilde University Hospital, Denmark.
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N
Maltbæk
Department of Clinical Physiology, Koege University Hospital, Denmark.
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AA
Buhl
Department of Surgery, Roskilde University Hospital, Denmark; Faculty of Health Sciences, University of Copenhagen, Denmark.
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O
Roikjær
D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography / Q000379:methods*; D011446:Prospective Studies; D015996:Survival Rate; D014057:Tomography, X-Ray Computed / Q000379:methods*
Colorectal cancer; Indeterminate lung lesion; PET/CT; Staging CT