The physiological functions of hydrogen sulfide (H 2 S) include vasorelaxation, stimulation of cellular bioenergetics, and promotion of angiogenesis. Analysis of human colon cancer biopsies and patient-matched normal margin mucosa revealed the selective upregulation of the H 2 S-producing enzyme cystathionine-β-synthase (CBS) in colon cancer, resulting in an increased rate of H 2 S production. Similarly, colon cancer-derived epithelial cell lines (HCT116, HT-29, LoVo) exhibited selective CBS up-regulation and increased H 2 S production, compared with the nonmalignant colonic mucosa cells, NCM356. CBS localized to the cytosol, as well as the mitochondrial outer membrane. ShRNA-mediated silencing of CBS or its pharmacological inhibition with aminooxyacetic acid reduced HCT116 cell proliferation, migration, and invasion; reduced endothelial cell migration in tumor/endothelial cell cocultures; and suppressed mitochondrial function (oxygen consumption, ATP turnover, and respiratory reserve capacity), as well as glycolysis. Treatment of nude mice with aminooxyacetic acid attenuated the growth of patientderived colon cancer xenografts and reduced tumor blood flow. Similarly, CBS silencing of the tumor cells decreased xenograft growth and suppressed neovessel density, suggesting a role for endogenous H 2 S in tumor angiogenesis. In contrast to CBS, silencing of cystathionine-γ-lyase (the expression of which was unchanged in colon cancer) did not affect tumor growth or bioenergetics. In conclusion, H 2 S produced from CBS serves to (i) maintain colon cancer cellular bioenergetics, thereby supporting tumor growth and proliferation, and (ii) promote angiogenesis and vasorelaxation, consequently providing the tumor with blood and nutritients. The current findings identify CBS-derived H 2 S as a tumor growth factor and anticancer drug target.

Significance: Cancer represents a major socioeconomic problem; there is a significant need for novel therapeutic approaches targeting tumor-specific pathways. Recent Advances: In colorectal and ovarian cancers, an increase in the intratumor production of hydrogen sulfide (H 2 S) from cystathionine b-synthase (CBS) plays an important role in promoting the cellular bioenergetics, proliferation, and migration of cancer cells. It also stimulates peritumor angiogenesis inhibition or genetic silencing of CBS exerts antitumor effects both in vitro and in vivo, and potentiates the antitumor efficacy of anticancer therapeutics. Critical Issues: Recently published studies are reviewed, implicating CBS overexpression and H 2 S overproduction in tumor cells as a tumorgrowth promoting ''bioenergetic fuel'' and ''survival factor,'' followed by an overview of the experimental evidence demonstrating the anticancer effect of CBS inhibition. Next, the current state of the art of pharmacological CBS inhibitors is reviewed, with special reference to the complex pharmacological actions of aminooxyacetic acid. Finally, new experimental evidence is presented to reconcile a controversy in the literature regarding the effects of H 2 S donor on cancer cell proliferation and survival. Future Directions: From a basic science standpoint, future directions in the field include the delineation of the molecular mechanism of CBS upregulation of cancer cells and the delineation of the interactions of H 2 S with other intracellular pathways of cancer cell metabolism and proliferation. From the translational science standpoint, future directions include the translation of the recently emerging roles of H 2 S in cancer into human diagnostic and therapeutic approaches. Antioxid. Redox Signal. 22,

Preoperative lymphoscintigraphy and meticulous intraoperative search for blue/radioactive nodes may improve results in H&N melanomas.

SLN biopsy alone is associated with significantly less morbidity compared with SLN biopsy plus CLND.

As age increases, so does Breslow thickness, the incidence of ulceration and regression, and the proportion of male patients-all poor prognostic factors. However, the frequency of SLN metastasis declines with increasing age. It is not known whether this represents a decreased sensitivity (higher false-negative rate) of the SLN procedure in older patients or a different biological behavior (hematogenous spread) of melanomas in older patients.

ObjectiveTo determine the optimal radioactive colloid injection technique for sentinel lymph node (SLN) biopsy for breast cancer. Summary Background DataThe optimal radioactive colloid injection technique for breast cancer SLN biopsy has not yet been defined. Peritumoral injection of radioactive colloid has been used in most studies. Although dermal injection of radioactive colloid has been proposed, no published data exist to establish the false-negative rate associated with this technique. MethodsThe University of Louisville Breast Cancer Sentinel Lymph Node Study is a multiinstitutional study involving 229 surgeons. Patients with clinical stage T1-2, N0 breast cancer were eligible for the study. All patients underwent SLN biopsy, followed by level I/II axillary dissection. Peritumoral, subdermal, or dermal injection of radioactive colloid was performed at the discretion of the operating surgeon. Peritumoral injection of isosulfan blue dye was performed concomitantly in most patients. The SLN identification rates and false-negative rates were compared. The ratios of the transcutaneous and ex vivo radioactive SLN count to the final background count were calculated as a measure of the relative degree of radioactivity of the nodes. One-way analysis of variance and chisquare tests were used for statistical analysis. ResultsA total of 2,206 patients were enrolled. Peritumoral, subdermal, or dermal injection of radioactive colloid was performed in 1,074, 297, and 511 patients, respectively. Most of the patients (94%) who underwent radioactive colloid injection also received peritumoral blue dye injection. The SLN identification rate was improved by the use of dermal injection compared with subdermal or peritumoral injection of radioactive colloid. The false-negative rates were 9.5%, 7.8%, and 6.5% (not significant) for peritumoral, subdermal, and dermal injection techniques, respectively. The relative degree of radioactivity of the SLN was five-to sevenfold higher with the dermal injection technique compared with peritumoral injection. ConclusionsDermal injection of radioactive colloid significantly improves the SLN identification rate compared with peritumoral or subdermal injection. The false-negative rate is also minimized by the use of dermal injection. Dermal injection also is associated with SLNs that are five-to sevenfold more radioactive than with peritumoral injection, which simplifies SLN localization and may shorten the learning curve.

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ObjectiveTo determine the optimal experience required to minimize the false-negative rate of sentinel lymph node (SLN) biopsy for breast cancer. Summary Background DataBefore abandoning routine axillary dissection in favor of SLN biopsy for breast cancer, each surgeon and institution must document acceptable SLN identification and false-negative rates. Although some studies have examined the impact of individual surgeon experience on the SLN identification rate, minimal data exist to determine the optimal experience required to minimize the more crucial false-negative rate. MethodsAnalysis was performed of a large prospective multiinstitutional study involving 226 surgeons. SLN biopsy was performed using blue dye, radioactive colloid, or both. SLN biopsy was performed with completion axillary LN dissection in all patients. The impact of surgeon experience on the SLN identification and false-negative rates was examined. Logistic regression analysis was performed to evaluate independent factors in addition to surgeon experience associated with these outcomes. ResultsA total of 2,148 patients were enrolled in the study. Improvement in the SLN identification and false-negative rates was found after 20 cases had been performed. Multivariate analysis revealed that patient age, nonpalpable tumors, and injection of blue dye alone for SLN biopsy were independently associated with decreased SLN identification rates, whereas upper outer quadrant tumor location was the only factor associated with an increased false-negative rate. ConclusionsSurgeons should perform at least 20 SLN cases with acceptable results before abandoning routine axillary dissection. This study provides a model for surgeon training and experience that may be applicable to the implementation of other new surgical technologies.Sentinel lymph node (SLN) biopsy has become increasingly accepted as a minimally invasive alternative to level I/II axillary dissection for the staging of breast cancer. Because approximately 70% of patients with clinical stage T1 to 2, N0 breast cancer have pathologically negative axillary nodes, SLN biopsy has the potential to eliminate the complications of axillary dissection in most patients. Patients with axillary metastasis are then selected for completion axillary dissection.There are two key parameters of successful SLN biopsy: the SLN identification rate and the false-negative rate. The