ObjectivesTo estimate the diagnostic accuracy of sentinel node biopsy (SNB) combined with preoperative 18 F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) for inguinal lymph node (LN) evaluation in patients with invasive penile squamous cell carcinoma (PSCC) with no clinical evidence of inguinal metastases (cN0) at two tertiary centres with complete clinical follow-up. Patients and MethodsFrom April 2010 in Centre one and from January 2013 in Centre two, we prospectively enrolled patients diagnosed with invasive PSCC and scheduled for SNB at the only two university centres treating penile cancer in Denmark. All patients had FDG PET/CT before SNB. The sentinel LNs were preoperatively located by planar lymphoscintigraphy in 134 groins (68 patients) and by single-photon emission CT/ CT in 120 groins (61 patients). The primary endpoints were the sensitivity, specificity, and false-negative rate of SNB combined with FDG PET/CT. The secondary endpoint was SNB-related morbidity. ResultsWe examined 254 groins in 129 patients by SNB combined with FDG PET/CT. The median (interquartile range, IQR) follow-up of survivors was 23 (14-35) months. Of 201 LNnegative groins, two were false negatives, and despite radiochemotherapy treatment, both patients died from penile cancer. Four of 23 radiotracer-silent groins, had a FDG PET/CT-positive LNs and were surgically explored. In one of four of the explored groins, a positive LN was found. Combined FDG PET/CT-SNB sensitivity was 94.4% (95% confidence interval [CI] 81-99%) per groin. The falsenegative rate was 5.6% (95% CI 1-19%) per groin. In 15 patients (11.6%) there were 25 SNB-related complications of Clavien-Dindo grades I-IIIa. The only Clavien-Dindo IIIa complication was an inguinal lymphocele treated by aspiration. ConclusionIn this study, we present a favourable SNB false-negative rate of 5.6% in a national cohort of clinically LN-negative patients with invasive PSCC with a pre-SNB FDG PET/CT scan. The combination of FDG PET/CT and SNB seems to be a promising diagnostic approach. Even so, a false-negative SNB was fatal in two of two cases and we are determined to continue the development of our SNB technique. The SNBrelated morbidity was limited.

Objectives To evaluate diagnostic accuracy of 18F‐fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) compared to contrast‐enhanced CT in assessment of inguinal lymph node (ILN) metastases, distant metastases and synchronous cancers in patients with penile squamous cell carcinoma (pSCC). Patients and Methods During a 4‐year period, patients with pSCC were scheduled for FDG PET/CT prior to surgical treatment at two referral centres that manage all penile cancers in Denmark. The primary endpoint was diagnostic accuracy of FDG PET/CT and of CT alone with histopathology or Response Evaluation Criteria In Solid Tumors (RECIST) as reference. Results We evaluated 171 patients for distant metastases and synchronous incident cancers and examined 286 groins in 143 patients for LN metastases by FDG PET/CT. Six groins disclosed false negatives. FDG PET/CT sensitivity was 85.4% per patient. In 135 patients (270 groins), CT images were evaluated separately and 22 groins disclosed false negatives. CT sensitivity was 47.5% per patient. FDG PET/CT detected pSCC distant metastases in seven patients. Distant metastases from other cancers were newly detected in three patients. In eight patients, an incidental synchronous cancer was detected. Seven out of the 18 distant malignancies detected depended on FDG PET information. Conclusion This study underlines the increased diagnostic accuracy of FDG PET/CT compared to CT alone in the evaluation of ILN status. In patients with palpable LNs, the advantage of FDG PET/CT over CT is less pronounced. FDG PET/CT may play a role in penile cancer evaluation.

By adding PET scans to the CT evaluation of patients treated with DC vaccines, a more detailed picture of the single lesions was found. This seems to improve the clinical evaluation of the treatment. The lack of correlation between the PET and CT scans suggests that some of the increases in target lesions seen in CT scans might be due to oedema or immune-infiltrates and not progression of the disease. Thus, further investigation into the contribution of PET scans to the evaluation of cancer immunotherapy is needed.

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