Detection of additional primary malignant tumor in cancer survivors: the use of PET/CT for image-guided biopsy

Abstract

Background PET/CT is a well-established tool in the diagnostic workup of oncology patients. With the advance in diagnosis and therapy of oncology patients, survivors are at risk of developing additional malignancies. This study aimed to evaluate the yield of 18F-FDG PET/CT in biopsy guidance for the detection of unexpected additional primary malignancies in patients with known primary cancers. Medical records of patients underwent 18F-FDG PET/CT scans from July 2015 to December 2017 were reviewed, and 644 patients (346 men and 298 women; mean age 59.7, age range from 21: 78) who had been scanned for known cancers were included in this study. Lesions that were newly detected on PET/CT had not been previously detected by other modalities and were atypical in location for metastases were interpreted as suggestive of a new primary malignant tumor. These image findings guide the biopsy for histopathology, immune-histochemistry to confirm the diagnosis. Results PET-positive findings suggestive of new primary malignant tumors were found in 30 (4.67%) of 644 patients. In 21 (3.26%) of 644 patients, these lesions were pathologically proven to be malignant (20 true positive and 1 case false negative). Proven sites were lung (5 cases), colorectal (5 cases), breast (2 case), liver (2 cases), head and neck (2 cases), anal (1 cases), gastric (1 case), lymphoma (1 case), esophagus (1 case), and prostate (1 case). In 9/30 (30%) patients suspected to have additional primary, PET was falsely positive. Biopsy was taken for histology and immune-histochemistry with follow-up record that confirms the diagnosis to validate the PET/CT findings. Conclusions With the use of 18-F FDG PET/CT image- guided biopsy, additional primary malignancies were detected in at least 3.26% of oncology patients; thus, patient cure is possible if such malignancies are treated promptly and aggressively.

Importance of PET/CT in Initial Workup of Head and Neck Squamous Cell Carcinoma

“…Shaban and Saleh investigated the rate of second primary malignancies on PET/CT imaging for patients with a known primary malignancy. They found that 4.67% of PET/CT scans had findings suggestive of a second primary, with a false positive rate of 31% 21 . Given the potential delay in treatment for the primary lesion, additional studies comparing cost and time to treatment should be conducted.…”

“…They found that 4.67% of PET/CT scans had findings suggestive of a second primary, with a false positive rate of 31%. 21 Given the potential delay in treatment for the primary lesion, additional studies comparing cost and time to treatment should be conducted. Clinicians must carefully balance the workup of incidental findings while simultaneously preparing the patient for treatment of their primary lesion.…”