Lessons learned from histological step-sectioning of sentinel lymph nodes in penile cancer.

AIMS: Histopathological examination of sentinel lymph nodes in penile cancer has varied during the first 10 years after introduction of the dynamic sentinel node (SLN) procedure in Denmark, and guidelines have been sparse. The aim of this study was to investigate the impact of rigorous step-sectioning of sentinel lymph nodes in penile cancer and improve guidelines. METHODS AND RESULTS: Seventy-two penile squamous cell carcinoma patients undergoing SLN procedure at a single institution in 2000-2010 were included. The archived lymph node tissues already subjected to a standard pathological examination were retrieved and the initially negative lymph nodes were subjected to an extended step-sectioning procedure. The results were compared to clinical patient outcome from a national database and subsequent pathology reports. The original histopathological examination had detected 26 SLN with metastasis, 21 macro metastases and five micro metastases. The additional step-sectioning procedure of this study generated 4606 slides; seven SLN metastases, two macro metastases and five micro metastases, were detected. One of the macro metastases originated from a patient in which a clinical relapse had occurred in the same groin. None of the other metastases detected in this study showed ipsilateral relapse during follow-up. CONCLUSION: The results underline the value of our current practice of step-sectioning sentinel lymph nodes in penile cancer and the need for histopathological routines and guidelines. The Danish national guidelines on histopathological handling of sentinel lymph nodes have been adapted to detect any potential clinically relevant metastases.

DaPeCa-3: promising results of sentinel node biopsy combined with (18) F-fluorodeoxyglucose positron emission tomography/computed tomography in clinically lymph node-negative patients with penile cancer - a national study from Denmark.

OBJECTIVES: To 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 METHODS: From 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. RESULTS: We 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 LN-negative groins, two were false negatives, and despite radio-chemotherapy 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 false-negative 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. CONCLUSION: In 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 SNB-related morbidity was limited.

DaPeCa-1: diagnostic accuracy of sentinel lymph node biopsy in 222 patients with penile cancer at four tertiary referral centres - a national study from Denmark.

OBJECTIVES: To estimate the diagnostic accuracy of sentinel lymph node biopsy (SNB) in patients with penile cancer and assess SNB complications in a national multicentre setting. PATIENTS AND METHODS: Retrospectively data were collected from records in four university centres by one medical doctor covering all SNBs performed in Denmark between 1 January 2000 and 31 December 2010. Patients had either impalpable lymph nodes (LNs) in one or both groins, or had a palpable inguinal mass from which aspiration cytology failed to reveal malignancy. Patients were injected with nanocolloid technetium and had a scintigram recorded before the SNB. The primary endpoint was LN recurrence on follow-up. The secondary endpoint was complications after SNB. Diagnostic accuracy was computed. RESULTS: In all, 409 groins in 222 patients were examined by SNB. The median (interquartile range) follow-up of patients who survived was 6.6 (5-10) years. Of 343 negative groins, eight were false negatives. The sensitivity was 89.2% (95% confidence interval 79.8-95.2%) per groin. Interestingly, four of 67 T1G1 patients had a positive SNB. In all, 28 of 222 (13%) patients had complications of Clavien-Dindo grade I-IIIa. CONCLUSION: Penile cancer SNB with a close follow-up stages LN involvement reliably and has few complications in a national multicentre setting. Inguinal LN dissection was avoided in 76% of patients.

Centralization and Equitable Care in Rare Urogenital Malignancies: The Case for Penile Cancer.

Centralization of specialized care for rare cancers can improve patient outcomes. Inguinal lymph node evaluation is the most important clinical aspect of penile cancer care and is often neglected in a decentralized setting. Centralization of care may reduce system delays, improve guideline adherence, provide access to a wider team of specialists, and improve prognosis, albeit with some inconveniences for patients. PATIENT SUMMARY: We reviewed evidence for the centralization of care for penile cancer. Patients may have to travel greater distances to receive specialized care in expert centers. However, centralization means that rare cancers can be treated by more experienced surgeons, which can yield better outcomes in terms of survival and penis-preserving or reconstruction surgery.

Basolateral Na+-dependent HCO3- transporter NBCn1-mediated HCO3- influx in rat medullary thick ascending limb.

The electroneutral Na(+)-dependent HCO3- transporter NBCn1 is strongly expressed in the basolateral membrane of rat medullary thick ascending limb cells (mTAL) and is up-regulated during NH4(+)-induced metabolic acidosis. Here we used in vitro perfusion and BCECF video-imaging of mTAL tubules to investigate functional localization and regulation of Na(+)-dependent HCO3- influx during NH4(+)-induced metabolic acidosis. Tubule acidification was induced by removing luminal Na+ (DeltapHi: 0.88 +/- 0.11 pH units, n = 10). Subsequently the basolateral perfusion solution was changed to CO2/HCO3- buffer with and without Na+. Basolateral Na(+)-H+ exchange function was inhibited with amiloride. Na(+)-dependent HCO3- influx was determined by calculating initial base flux of Na(+)-mediated re-alkalinization. In untreated animals base flux was 8.4 +/- 0.9 pmol min(-1) mm(-1). A 2.4-fold increase of base flux to 21.8 +/- 3.2 pmol min(-1) mm(-1) was measured in NH4(+)-treated animals (11 days, n = 11). Na(+)-dependent re-alkalinization was significantly larger when compared to control animals (0.38 +/- 0.03 versus 0.22 +/- 0.02 pH units, n = 10). In addition, Na(+)-dependent HCO3- influx was of similar magnitude in chloride-free medium and also up-regulated after NH4+ loading. Na(+)-dependent HCO3- influx was not inhibited by 400 microm DIDS. A strong up-regulation of NBCn1 staining was confirmed in immunolabelling experiments. RT-PCR analysis revealed no evidence for the Na(+)-dependent HCO3- transporter NBC4 or the two Na(+)-dependent CI-/HCO3- exchangers NCBE and NDCBE. These data strongly indicate that rat mTAL tubules functionally express basolateral DIDS-insensitive NBCn1. Function and protein are strongly up-regulated during NH4(+)-induced metabolic acidosis. We suggest that NBCn1-mediated basolateral HCO3- influx is important for basolateral NH3 exit and thus NH4+ excretion by means of setting pHi to a more alkaline value.

Functional up-regulation of basolateral Na+-dependent HCO3- transporter NBCn1 in medullary thick ascending limb of K+-depleted rats.

The electroneutral, Na(+)-coupled HCO(3)(-) co-transporter (NBCn1) is expressed in the basolateral membrane of rat medullary thick ascending limb (mTAL) segments and is up-regulated strongly during metabolic acidosis. We have suggested previously that NBCn1-mediated HCO(3)(-) uptake across the basolateral cell membrane is an important buffering mechanism during the transcellular transport of NH(4)(+) in the mTAL. To investigate this further we treated rats with a low-K(+) diet for 4 days, a manoeuvre known to increase proximal tubular ammoniagenesis and delivery of luminal NH(4)(+) to the mTAL. Hypokalaemia strongly increased immunolabelling of basolateral NBCn1 in the mTAL of the inner stripe of the outer medulla. Immunoblotting revealed an eightfold up-regulation of NBCn1 protein in K(+)-depleted rats. Subsequently we used in vitro perfusion of isolated mTAL and BCECF imaging to investigate Na(+)-coupled HCO(3)(-) influx in normal and K(+)-depleted rats. Hypokalaemia induced a threefold up-regulation of Na(+)-coupled HCO(3)(-) influx (1.64+/-0.28 vs. 0.47+/-0.05 pH units/minute, n=8). The Na(+)-dependent alkalinization was also significantly larger in K(+)-depleted rats (0.38+/-0.04 vs. 0.23+/-0.03 pH units). These data indicate that K(+)-depleted rats respond with a strong up-regulation of NBCn1 protein and function, probably to cope with the higher tubular load of NH(4)(+), and strengthen our previous suggestion that NBCn1 is an important player in the excretion of NH(4)(+). They also indicate that it is the delivery of luminal NH(4)(+) rather than systemic changes of pH that determine the expression of NBCn1.