Global Forum of Cancer Surgeons: Cancer Surgery During the COVID-19 Pandemic: Impact and Lessons Learned

Background

The purpose of this article is to summarize the opinions of the surgical oncology leaders from the Global Forum of Cancer Surgeons (GFCS) about the global impact of COVID-19 pandemic on cancer surgery.

Methods

A panel session (virtual) was held at the annual Society of Surgical Oncology 2021 International Conference on Surgical Cancer Care to address the impact of COVID-19 on cancer surgery globally. Following the virtual meeting, a questionnaire was sent to all the leaders to gather additional opinions. The input obtained from all the leaders was collated and analyzed to understand how cancer surgeons from across the world adapted in real-time to the impact of COVID-19 pandemic.

Results

The surgical oncology leaders noted that the COVID-19 pandemic led to severe disruptions in surgical cancer care across all domains of clinical care, education, and research. Several new changes/protocols associated with increased costs were implemented to deliver safe care. Leaders also noted that preexisting disparities in care were exacerbated, and the pandemic had a detrimental effect on well-being and financial status.

Conclusions

The COVID-19 pandemic has led to severe disruptions in surgical cancer care globally. Leaders of the GFCS opined that new strategies need to be implemented to prepare for any future catastrophic events based on the lessons learned from the current events. The GFCS will embark on developing such a roadmap to ensure that surgical cancer care is preserved in the future regardless of any catastrophic global events.

Antimicrobial regimens used in the treatment of mandibular fractures in UK maxillofacial units: changes over 12 years

In the case of most mandibular fractures, the prescription of antimicrobials for more than 24 hours postoperatively confers no clinical benefit. To establish the prescribing patterns for mandibular fractures in UK OMFS units, and to compare them with those used 12 years ago, we did a telephone and email survey of OMFS units in the UK. Antimicrobials were prescribed for more than 24 hours postoperatively by 76 units (65%) (considerably fewer than the 82 (87%) in 2005). The most commonly prescribed first-line antimicrobial was co-amoxiclav (75%). Although there has been some improvement since 2005, most units still prescribe antimicrobials for periods longer than 24 hours. National collaboration may improve their appropriate prescription.

Design, Synthesis, and Biological Activity of 1,2,3-Triazolobenzodiazepine BET Bromodomain Inhibitors

A number of diazepines are known to inhibit bromo- and extra-terminal domain (BET) proteins. Their BET inhibitory activity derives from the fusion of an acetyl-lysine mimetic heterocycle onto the diazepine framework. Herein we describe a straightforward, modular synthesis of novel 1,2,3-triazolobenzodiazepines and show that the 1,2,3-triazole acts as an effective acetyl-lysine mimetic heterocycle. Structure-based optimization of this series of compounds led to the development of potent BET bromodomain inhibitors with excellent activity against leukemic cells, concomitant with a reduction in c-MYC expression. These novel benzodiazepines therefore represent a promising class of therapeutic BET inhibitors.

Functional interdependence of BRD4 and DOT1L in MLL leukemia

Targeted therapies against disruptor of telomeric silencing 1-like (DOT1L) and bromodomain-containing protein 4 (BRD4) are currently being evaluated in clinical trials. However, the mechanisms by which BRD4 and DOT1L regulate leukemogenic transcription programs remain unclear. Using quantitative proteomics, chemoproteomics and biochemical fractionation, we found that native BRD4 and DOT1L exist in separate protein complexes. Genetic disruption or small-molecule inhibition of BRD4 and DOT1L showed marked synergistic activity against MLL leukemia cell lines, primary human leukemia cells and mouse leukemia models. Mechanistically, we found a previously unrecognized functional collaboration between DOT1L and BRD4 that is especially important at highly transcribed genes in proximity to superenhancers. DOT1L, via dimethylated histone H3 K79, facilitates histone H4 acetylation, which in turn regulates the binding of BRD4 to chromatin. These data provide new insights into the regulation of transcription and specify a molecular framework for therapeutic intervention in this disease with poor prognosis.

BET inhibitor resistance emerges from leukaemia stem cells

Bromodomain and extra terminal protein (BET) inhibitors are first-in-class targeted therapies that deliver a new therapeutic opportunity by directly targeting bromodomain proteins that bind acetylated chromatin marks. Early clinical trials have shown promise, especially in acute myeloid leukaemia, and therefore the evaluation of resistance mechanisms is crucial to optimize the clinical efficacy of these drugs. Here we use primary mouse haematopoietic stem and progenitor cells immortalized with the fusion protein MLL-AF9 to generate several single-cell clones that demonstrate resistance, in vitro and in vivo, to the prototypical BET inhibitor, I-BET. Resistance to I-BET confers cross-resistance to chemically distinct BET inhibitors such as JQ1, as well as resistance to genetic knockdown of BET proteins. Resistance is not mediated through increased drug efflux or metabolism, but is shown to emerge from leukaemia stem cells both ex vivo and in vivo. Chromatin-bound BRD4 is globally reduced in resistant cells, whereas the expression of key target genes such as Myc remains unaltered, highlighting the existence of alternative mechanisms to regulate transcription. We demonstrate that resistance to BET inhibitors, in human and mouse leukaemia cells, is in part a consequence of increased Wnt/β-catenin signalling, and negative regulation of this pathway results in restoration of sensitivity to I-BET in vitro and in vivo. Together, these findings provide new insights into the biology of acute myeloid leukaemia, highlight potential therapeutic limitations of BET inhibitors, and identify strategies that may enhance the clinical utility of these unique targeted therapies.

Myocardial substrate metabolism in obesity

Obesity is linked to a wide variety of cardiac changes, from subclinical diastolic dysfunction to end-stage systolic heart failure. Obesity causes changes in cardiac metabolism, which make ATP production and utilization less efficient, producing functional consequences that are linked to the increased rate of heart failure in this population. As a result of the increases in circulating fatty acids and insulin resistance that accompanies excess fat storage, several of the proteins and genes that are responsible for fatty acid uptake and metabolism are upregulated, and the metabolic machinery responsible for glucose utilization and oxidation are inhibited. The resultant increase in fatty acid metabolism, and the inherent alterations in the proteins of the electron transport chain used to create the gradient needed to drive mitochondrial ATP production, results in a decrease in efficiency of cardiac work and a relative increase in oxygen usage. These changes in cardiac mitochondrial metabolism are potential therapeutic targets for the treatment and prevention of obesity-related heart failure.

Effects of weight loss on myocardial energetics and diastolic function in obesity

A reduced myocardial phosphocreatine/adenosine triphosphate (PCr/ATP) ratio is linked to both diastolic dysfunction and heart failure. Although obesity is well known to cause diastolic dysfunction a link to impaired cardiac energetics has only recently been established. We assessed whether or not long-term weight loss in obesity, which is known to reduce mortality, is accompanied by both improved cardiac energetics and diastolic function. Normal weight (BMI 22 ± 2; n = 18) and obese subjects (BMI 34 ± 4; n = 13) underwent cine-MRI (1.5 Tesla) to determine left ventricular diastolic function using volume-time curve analysis, and (31)P-MR spectroscopy (3 Tesla) to assess cardiac energetics (PCr/ATP ratio). Obese subjects (n = 13) underwent repeat assessment after 1 year of supervised weight loss. Obesity, in the absence of identifiable cardiovascular risk factors, was associated with significantly impaired myocardial high energy phosphate metabolism (PCr/ATP ratio, normal; 2.03 ± 0.27 vs. obese; 1.58 ± 0.47, p = 0.002) and significantly lower peak diastolic filling rate (normal; 4.8 ± 0.8 vs. obese; 3.8 ± 0.7 EDV/s, p = 0.01). Weight loss (on average 9 kg, 55% excess weight) over 1 year resulted in a 24% increase in PCr/ATP ratio (p = 0.01) and an 18% improvement in peak diastolic filling rate (p = 0.01). Myocardial PCr/ATP ratio remained positively correlated with peak diastolic filling rate after weight loss (r = 0.63, p = 0.02). In obesity, weight loss improves impaired cardiac energetics and myocardial relaxation. Improved myocardial energetics appear to play a key role in diastolic functional recovery accompanying weight loss.

Nerve cuff stimulation and the effect of fascicular organization for hand grasp in nonhuman primates

The overall goal of this work is to introduce nerve cuff electrodes into upper extremity hand grasp systems. The first challenge is to develop a nerve cuff electrode that can selectively activate multiple hand functions from common upper extremity peripheral nerves. The Flat Interface Nerve Electrode (FINE) has shown selective stimulation capability in animal trials. The FINE wraps around the nerve and gently reshapes the nerve and aligns the fascicles within the nerve. Our hypothesis is that the FINE can selectively stimulate multi-fascicular nerves in the human upper extremity resulting in selective hand function. To assess the ability of the FINE to produce control of a hand with many degrees of freedom, we have tested the FINE in nonhuman primates. Fascicular organization and fascicle count are important factors to consider when determining electrode placement. The proximal nerve is an attractive electrode location to access both extrinsic and intrinsic muscles in the upper extremity. A challenge with the nonhuman primate model is that the nonhuman primate median and ulnar nerves both have uni-fascicular regions proximally. The human proximal median and ulnar nerves have an encouraging anatomy of multi-fasciculated nerves with redundant fascicles that may result in more selective hand function than is capable in the nonhuman primate.

Carcinoid tumors of the gastrointestinal tract. A review and the Duke University institutional overview

Carcinoid tumors are relatively rare neoplasms arising from the amine precursor uptake and decarboxylation (APUD) cells of the gastrointestinal tract and bronchial tree. Presenting symptoms vary by site of origin, and various modalities may be used to diagnose them. Initial treatment is surgical, with procedure depending upon site of origin. Several experimental therapies may be used in treatment of metastatic carcinoid tumors.

Improved clean-up for the determination of lasalocid in 'difficult' food matrices

Methodology has been developed for the determination of lasalocid in analytically 'difficult' matrices such as processed and spiced foods. The procedure was based on an existing silica-based solid-phase extraction (SPE) clean-up to which was added a novel NH2 SPE step before HPLC with fluorescence detection. Use of the additional step enabled the determination of lasalocid in matrices such as baby food, meat pies ('pasties'), etc. Analysis of these matrices was not possible using the standard clean-up on its own. Chromatography showed a massive reduction in the amount of co-extractives and interferences. Validation data were obtained down to the 10-40 mg kg(-1) level for a range of products. Recoveries ranged from 74% at 10 microg kg(-1) for pork sausages to 96% at 40 microg kg(-1) for meat pies.

Changes in soil quality and below-ground carbon storage with conversion of traditional agricultural crop lands to bioenergy crop production

Berm-isolated (0.5 ha) plots have been used since 1995 to quantify changes in soil and water quality with conversion from agricultural to bioenergy crops. Soil quality improvements, including increases in soil carbon storage, have occurred on sites planted to woody or herbaceous species, and no-till corn compared with tilled corn or cotton. Initial increases in soil carbon occurred within the upper 10 cm of the soil profile. Soil carbon on plantings of switchgrass, no-till corn, and sweetgum with a cover crop between the rows increased over the first 3 years. Soil carbon decreased by 6% on the sweetgum plantings without a cover crop and remained lower through the fifth growing season. Overall, the greatest increases in below ground carbon storage have occurred primarily within the upper 40 cm. Former land use, growth characteristics, management practices, and soil characteristics appear to be the primary factors determining the timing, depth. and extent of changes in soil carbon storage for bioenergy and no-till crops.

Intracranial metastatic parathyroid carcinoma: case report

OBJECTIVE AND IMPORTANCE

Parathyroid carcinoma is a rare entity, and fewer than 200 cases have been described. It is a slowly progressive disease characterized by frequent recurrences and local metastases. Most patients with parathyroid carcinoma die from metabolic complications of hyperparathyroidism. Five-year survival rates range from 25 to 50%. Functional parathyroid carcinoma is a rare cause of hyperparathyroidism that affects only 0.32 to 5% of all patients who undergo surgery for hypercalcemia. A review of the literature revealed only one other reported case of metastatic intracranial parathyroid carcinoma, in a patient who experienced local recurrence and metastatic disease when she was diagnosed with an intracranial lesion.

CLINICAL PRESENTATION

We report the case of a 44-year-old African-American man with recent-onset, right lower-extremity weakness and hypercalcemia 4 years after he underwent a parathyroidectomy for parathyroid carcinoma. At presentation, his parathyroid level was 467 pg/ml, and his serum calcium level was 15.2 mg/dl. Imaging studies revealed an isolated enhancing left mesial frontoparietal mass. A systemic Cardiolite study demonstrated a single focus of radiotracer uptake in this region. No abnormal uptake was demonstrated in the neck or elsewhere.

INTERVENTION

The patient underwent a frameless stereotactic interventional magnetic resonance imaging-guided resection via a parasagittal interhemispheric approach. Pathological findings were consistent with parathyroid carcinoma. After resection, his right lower-extremity weakness and secondary hyperparathyroidism resolved.

CONCLUSION

The typical natural history of parathyroid carcinoma concludes with death from complications of hyperparathyroidism. This case report supports aggressive surgical management to eliminate all parathyroid hormone-secreting malignant tissue and prevent metabolic complications. In this patient, intraoperative magnetic resonance imaging was helpful to ensure complete resection.

Interventional MRI-guided stereotactic aspiration of acute/subacute intracerebral hematomas

Surgical interventions for hypertensive intracerebral hematomas are still controversial. Many believe only hyperacute intervention is of any real utility. The majority of present interventions require a formal craniotomy with standard neurosurgical techniques. There are, however, a few reports on CT-guided stereotactic aspiration of these hematomas with favorable results. We report 10 patients treated with frameless fiduciless stereotactic means using an intraoperative MRI scanner (GE 0.5 T Signa SP). These patients were initially diagnosed as having hypertensive intracerebral hematoma and operated on within 1-34 days after hemorrhage. The actual operating time averaged less than 120 min, including intraoperative imaging. Clot volumes ranged from 2.5 to 75 cm(3) with a mean of 31 cm(3). There were 2 thalamic hematomas and 8 basal gangliar hematomas. Three patients had intraventricular hematoma extension and all 3, as well as an additional patient, required extraventricular drainage. However, no patients required permanent posthemorrhage ventriculoperitoneal shunting. Aspiration was successful in all cases to 70-90% of clot removal. Two cases utilized intrahematoma t-PA infusion with subsequent 80-90% clot removal. There were no complications or rehemorrhages. All patients showed some form of improvement that included either improved blood pressure control, speech or cognitive abilities. We conclude that using an intraoperative MRI scanner to perform frameless, fiduciless stereotactic aspiration of acute/subacute intracerebral hematoma is a safe and potentially effective means of treating intracerebral hematomas.

A pilot study of preoperative continuous infusion 5-fluorouracil, external microwave hyperthermia, and external beam radiotherapy for treatment of locally advanced, unresectable, or recurrent rectal cancer

PURPOSE

To determine the feasibility of combining external beam radiotherapy, continuous infusion 5-fluorouracil (5-FU), and external microwave hyperthermia in patients with locally advanced, unresectable, or recurrent adenocarcinoma of the rectum.

METHODS AND MATERIALS

From 7/95 through 2/99, 15 patients were enrolled in the study. The treatment regimen consisted of continuous infusion 5-FU 250 mg/m(2)/d 7 days/week beginning on day 1, external beam radiotherapy to the pelvis, 4500 cGy, 180 cGy/d 5 days/week using a 3 or 4-field technique, and external microwave hyperthermia on days 3, 8, 15, 22, and 29. Chemotherapy was stopped on the last day of radiotherapy. Surgical resection, if feasible, was scheduled 3-6 weeks after completing thermochemoradiotherapy. For this regimen to be considered feasible, no more than 2 of the 15 patients should fail to complete therapy due to life-threatening toxicity. Toxicity was scored using National Cancer Institute Criteria.

RESULTS

All patients completed the chemoradiotherapy portion of the protocol. Eleven of the 15 patients completed all 5 hyperthermia treatments. Of the 4 patients who did not receive the full course of hyperthermia, only 1 patient had treatment stopped due to life-threatening toxicity. The other 3 patients did not complete hyperthermia due to scheduling errors (n = 2) or patient request (n = 1). Five of 15 patients required a treatment interruption due to toxicity > or = Grade 3. Seven patients experienced lesser degrees of toxicity which did not require treatment interruption. Three patients experienced no side effects. The most common toxicities were dermatitis and diarrhea. Of the 14 patients in whom surgery was planned, 11 (79%) were resectable. There was one pathologic complete response.

CONCLUSIONS

It is feasible to deliver thermochemoradiotherapy, as prescribed in this study, to patients with locally advanced, unresectable, or recurrent rectal cancer. The therapy is moderately toxic, with one-third of patients requiring temporary treatment interruptions. The regimen appears active against rectal cancer, and appears to warrant further consideration as a treatment option for this patient population.

Analysis of prognosis and disease progression after local recurrence of melanoma

BACKGROUND

Local recurrence of melanoma is associated with a grave prognosis. However, the characteristics and the mode of disease progression for patients with local recurrence have not been adequately addressed in the literature.

METHODS

A retrospective analysis of patients treated at a single institution revealed a subset of patients (n = 648) with local recurrence of melanoma as a first event. Patient characteristics, histologic determinants, and disease free interval were variables used to identify prognostic factors.

RESULTS

In this group of patients, male gender (P = 0. 0163), increasing age (P = 0.0001), head and neck primaries (P = 0. 0001), thicker Breslow depths (P = 0.0022), deeper Clark levels (P = 0.0010), and ulceration of the primary tumor (P = 0.0348) suggested a shorter time until local recurrence. Breslow depth (P = 0.0004), Clark level (P = 0.0043), and ulceration (P = 0.0001) still factored into the survival prognosis after recurrence. Truncal primaries (P = 0.0005) and shorter disease free intervals (P = 0.0098) were also associated with poorer outcomes after recurrence. Of the 648 patients, 124 showed no progression, 196 developed another local recurrence, 178 developed in-transit/lymph node metastases, and 150 had systemic recurrences. Survival was only 33.6% for patients with further metastases, compared with 77.4% for patients with no progression of disease after a median follow-up of 38.9 months.

CONCLUSIONS

There was a 48.5% mortality rate at 5 years of follow-up after local recurrence. Long term survival (> 10 years) was estimated to be 34.9%. The patterns of failure after local recurrence suggest that patients may benefit from aggressive locoregional therapy.

Timing of sentinel lymph node mapping after lymphoscintigraphy

BACKGROUND

Sentinel lymph node (SLN) mapping is an effective technique for staging patients with melanoma. In an attempt to avoid reinjection of radiolabeled colloid and facilitate SLN mapping at the time of surgery, we examined whether residual radioactivity from preoperative lymphoscintigraphy could be used to accurately identify SLNs during surgery 18 to 24 hours later.

METHODS

Forty-six patients with newly diagnosed melanoma underwent injection of 0.22-micron filtered technetium 99m-labeled sulfur colloid followed by lymphoscintigraphy. Patients returned the next day for SLN biopsy with Isosulfan blue dye and the hand-held gamma-probe to identify SLNs. Thirty of 46 patients underwent repeat imaging before operation. No patient had reinjection of radiocolloid.

RESULTS

Ninety-five SLNs were identified on initial lymphoscintigraphy, and repeat imaging on the day of surgery confirmed all SLNs previously identified. A total of 122 SLNs (2.65 per patient) were resected from 58 basins. Eighty-four (69%) of 122 SLNs stained blue, and 118 (97%) of 122 SLNs had in vivo gamma-counts greater than 4 times background. Microscopic metastases were present in 13 (10.7%) of 122 SLNs in 12 (26.1%) of 46 patients. There have been no recurrences over a mean follow-up time of 320 days.

CONCLUSIONS

Intraoperative gamma-probe detection combined with blue dye injection is highly effective in identifying SLNs 18 to 24 hours after injection of 0.22-micron filtered 99mTc-sulfur colloid. Reinjection of radiocolloid is not required. This technique avoids radiopharmaceutical administration in the operating room, minimizes radiation exposure, and increases scheduling flexibility.

Recurrent ductal carcinoma in situ after total mastectomy

A case report is presented of a woman with recurrent DCIS occurring several years following a total mastectomy, the diagnosis of which was aided by a subpectoral saline implant. A discussion of factors associated with recurrence and a review of the literature is provided. A role for selective use of mammography in screening postmastectomy reconstructed breasts in patients at high risk for recurrence is suggested.

Preoperative chemoradiation for patients with locally advanced adenocarcinoma of the pancreas

BACKGROUND

Improved resectability is a major theoretical benefit of preoperative chemoradiation for pancreatic cancer. Since 1994, patients at Duke University Medical Center with locally advanced pancreatic cancer have been treated with multimodality preoperative therapy. The purpose of this study was to review our experience with preoperative therapy for locally advanced pancreatic cancer and determine if an aggressive neoadjuvant regimen would not only downstage these tumors pathologically but also improve the odds of complete surgical resection.

METHODS

The charts of 25 patients treated with neoadjuvant chemoradiation at Duke University Medical Center with biopsy-proven, locally advanced adenocarcinoma of the pancreas were reviewed. Tumors were defined as locally advanced based on radiographic or intraoperative evidence of disease that abuts the superior mesenteric artery or vein (n = 22) or involves lymph nodes that are within the proposed radiation field (n = 3). All 25 patients received external beam radiotherapy (median dose 4500 cGy) in daily fractions of 180 cGy over 5 weeks. All patients concurrently received 5-fluorouracil (FU), and many also received mitomycin C or cisplatin, or both. Patients were given a 3- to 4-week break before a restaging computed tomographic (CT) scan was performed. Three patients were not restaged: one died from metastatic disease; one was reclassified as having a neuroendocrine tumor; and one was lost to follow-up.

RESULTS

On restaging after neoadjuvant therapy, 64% of patients had stable or decreased primary tumor size. Radiographically, two patients appeared potentially resectable, and seven others developed evidence of metastatic disease. Eight patients underwent exploration, but only five could be resected. Of the five patients resected, only one had negative margins and negative lymph nodes. This patient had significant pancreatitis on initial exploration. After neoadjuvant therapy, he had a complete response radiographically, and there was no residual cancer in his resection specimen. Pathologic examination of the other resection specimens suggested that despite significant tumor fibrosis, malignant cells persist even at the periphery of the lesions.

CONCLUSION

Although neoadjuvant chemoradiation has many theoretical advantages in managing pancreatic malignancy, true pathologic downstaging of locally advanced lesions into tumors that can be removed with negative nodes and margins appears to be a rare event with currently used therapeutic regimens.

Diagnosis of pancreatic carcinoma: role of FDG PET

OBJECTIVE

The purpose of this study was to investigate the role of positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) in differentiating benign from malignant disease in patients with possible pancreatic malignancy.

SUBJECTS AND METHODS

All patients with a possible diagnosis of pancreatic carcinoma based on CT or ERCP findings were eligible for inclusion in this prospective study. PET imaging of the abdomen was performed in 37 patients and was interpreted as positive if FDG activity in the pancreas exceeded background activity and as negative if activity was less than or equal to background activity. Semiquantitative analysis was performed by calculating a standardized uptake ratio. Studies were reviewed independently by two radiologists, and results were correlated with biopsy results and with CT and ERCP findings. Sensitivity and specificity of FDG PET for revealing pancreatic malignancy was determined.

RESULTS

FDG activity in the pancreas was increased in 24 patients, and adenocarcinoma was diagnosed in 22 of these patients (92%). Two patients (8%) with increased activity had benign disease, including one patient with chronic pancreatitis who showed no evidence of tumor at laparotomy and one patient with a mucinous cystic tumor who showed no malignant features at laparotomy. FDG uptake was low or normal in 13 patients, 10 of whom (77%) had benign disease. FDG uptake was also low in three patients with adenocarcinoma, whose tumor size ranged from 2 to 4 cm in diameter. The mean standardized uptake ratio value for malignant disease was 5.1 (range, 1.0-10.1) and for benign disease was 1.9 (range, 0.0-5.8) (p < .001). The sensitivity of FDG PET for revealing malignant disease in the pancreas was 88% and the specificity was 83%.

CONCLUSION

FDG PET is a sensitive and specific noninvasive technique for the diagnosis of pancreatic malignancy.

Mucosal melanoma of the female genitalia: a clinicopathologic study of forty-three cases at Duke University Medical Center

BACKGROUND

Mucosal melanoma of the female genitalia is a rare neoplasm. Only nine reports reviewing more than 40 patients have been published on this subject in the past 30 years. These lesions arise from melanocytes, which can be found within the mucosa lining the female genital tract. Surgical resection is the mainstay of therapy, with little use for other modalities except in palliative roles. The overall prognosis is poor, with reported 5-year survival rates usually below 50%.

METHODS

Forty-three patients with primary mucosal melanoma of the female genitalia seen at the Duke University Medical Center Melanoma Clinic during a 25-year period were studied retrospectively. Specific information was obtained from the patients' clinic charts and computerized databases.

RESULTS

Thirty vulvar, nine vaginal, and four cervical lesions were identified. The median age at diagnosis was 61.4 years. At initial presentation, two thirds of the patients had localized disease only. Tumor ulceration and thickness of the primary lesion had a measurable impact on prognosis, whereas the presence of regional metastases at presentation did not. All but one patient underwent resection with curative intent. The performance of radical operations did not improve outcome among patients with vulvar melanoma. Many of the treatment failures were the result of local recurrences, hinting at the need to improve local control. Despite therapy, the overall corrected 5-year survival rate was 54%.

CONCLUSIONS

Prospective multicenter trials for patients with vulvovaginal melanoma could be helpful in establishing uniform, standardized surgical protocols and delineating the applicability of new modalities and therapies, such as lymphoscintigraphy with sentinel node biopsy and high-dose interferon.

Reduction of nonstationary noise in telescope imagery using a support constraint

We demonstrate the use of image support constraints in a noise-reduction algorithm. Previous work has revealed serious limits to the use of support if image noise is wide-sense stationary in the frequency domain; we use simulation and numerical calculations to show these limits are removed for nonstationary noise generated by inverse-filtering adaptive optics image spectra. To quantify the noise reduction, we plot fractional noise removed by the proposed algorithm over a range of support sizes. We repeat this calculation for other noise sources with varying degrees of stationarity.

Episodic ocean-induced CO2 greenhouse on Mars: implications for fluvial valley formation

Pulses of CO2 injected into the martian atmosphere more recently than 4 Ga can place the atmosphere into a stable, higher pressure, warmer greenhouse state. One to two bar pulses of CO2 added to the atmosphere during the past several billion years are sufficient to raise global mean temperatures above 240 or 250 K for tens to hundreds of millions of years, even when accounting for CO2 condensation. Over time, the added CO2 is lost to carbonates, the atmosphere collapses and returns to its buffered state. A substantial amount of water could be transported during the greenhouse periods from the surface of a frozen body of water created by outflow channel discharges to higher elevations, despite global temperatures well below freezing. This water, precipitated as snow, could ultimately form fluvial valleys if deposition sites are associated with localized heat sources, such as magmatic intrusions or volcanoes. Thus, if outflow channel discharges were accompanied by the release of sufficient quantities of CO2, a limited hydrological cycle could have resulted that would have been capable of producing geomorphic change sufficient for fluvial erosion and valley formation. Glacial or periglacial landforms would also be a consequence of such a mechanism.

Sphingomyelin metabolism is developmentally regulated in rat lung

We investigated several indices involved in sphingomyelin metabolism in developing rat lung. The levels of sphingomyelin gradually increased during lung maturation, with highest levels observed postnatally. The content of sphingosine and ceramide, biologically active sphingomyelin degradation products, did not significantly change in microsomes during the prenatal period, but increased to peak levels in neonatal and adult lung, respectively. Sphingosine content increased 6-fold between the fetal (Day 21) and neonatal period. The developmental profiles of two enzymes involved in sphingomyelin synthesis, serine palmitoyltransferase and sphingomyelin synthase, were similar. Serine palmitoyltransferase activity increased progressively from the fetal to neonatal period, and plateaued at high levels in the adult lung. The activity of serine palmitoyltransferase correlated with the levels of endogenous sphingolipid in lung tissue. Sphingomyelin synthase activity also increased during fetal lung development, but attained highest levels at Day 21 gestation; postnatally, enzyme activity was detected at lower levels. The activities of the sphingolipid hydrolases, acid and neutral sphingomyelinase and acid and alkaline ceramidase, were elevated in fetal lung, thereafter declining to low levels after birth. Studies conducted in alveolar macrophages, fibroblasts, and alveolar type II epithelial cells revealed that these developmental changes in enzyme activities in lung tissue were also occuring globally at the cellular level and were not restricted to any specific cell population. These studies suggest that the developmental increase in lung sphingomyelin content is due to coordinate regulation of enzymes involved in the biosynthesis and degradation of sphingomyelin. These observations also suggest a regulatory role for serine palmitoyltransferase in the generation of long chain sphingoid bases.

cash4, a novel achaete-scute homolog induced by Hensen's node during generation of the posterior nervous system

In vertebrate embryos, the precursor cells of the central nervous system (CNS) are induced by signaling from the organizer region. Here we report the isolation of a novel vertebrate achaete-scute homolog, cash4, which is expressed in the presumptive posterior nervous system in response to such signaling. cash4 is first expressed in epiblast cells flanking the late-phase organizer (Hensen's node), which retains its ability to induce cash4 during regression to the caudal end of the embryo. We show that these node-derived signals can be mimicked in vivo by the activity of fibroblast growth factor (FGF). We demonstrate that cash4 can substitute for the achaete/scute genes in the fly and that it also has proneural activity in vertebrate embryos. Together these results suggest that cash4 functions as a proneural gene downstream of node-derived signals (including FGF) to promote the formation of the neural precursors that will give rise to the posterior CNS in the chick embryo.

Advances in prevention of radiation damage to visceral and solid organs in patients requiring radiation therapy of the trunk

BACKGROUND

As a part of multimodality therapy, many patients with tumors of the trunk receive radiation therapy. The major morbidity of this therapy is often secondary to incidental radiation damage to tissues adjacent to treatment areas.

METHODS

We detail our use of saline breast implants placed in polyglycolic acid mesh sheets to displace visceral and solid organs away from the radiation field.

RESULTS

Analysis of CT scans and dose volume histograms reveal that this technique successfully displaces uninvolved organs away from the radiation fields, thereby minimizing the radiation dose to such organs and tissues.

CONCLUSION

We believe this is a safe and efficacious method to prevent radiation damage to visceral and solid organs adjacent to trunk tumor sites.

A complete genome screen for genes predisposing to severe bipolar disorder in two Costa Rican pedigrees

Bipolar mood disorder (BP) is a debilitating syndrome characterized by episodes of mania and depression. We designed a multistage study to detect all major loci predisposing to severe BP (termed BP-I) in two pedigrees drawn from the Central Valley of Costa Rica, where the population is largely descended from a few founders in the 16th-18th centuries. We considered only individuals with BP-I as affected and screened the genome for linkage with 473 microsatellite markers. We used a model for linkage analysis that incorporated a high phenocopy rate and a conservative estimate of penetrance. Our goal in this study was not to establish definitive linkage but rather to detect all regions possibly harboring major genes for BP-I in these pedigrees. To facilitate this aim, we evaluated the degree to which markers that were informative in our data set provided coverage of each genome region; we estimate that at least 94% of the genome has been covered, at a predesignated threshold determined through prior linkage simulation analyses. We report here the results of our genome screen for BP-I loci and indicate several regions that merit further study, including segments in 18q, 18p, and 11p, in which suggestive lod scores were observed for two or more contiguous markers. Isolated lod scores that exceeded our thresholds in one or both families also occurred on chromosomes 1, 2, 3, 4, 5, 7, 13, 15, 16, and 17. Interesting regions highlighted in this genome screen will be followed up using linkage disequilibrium (LD) methods.