Prospects for monitoring freshwater ecosystems towards the 2010 targets.

Human activities have severely affected the condition of freshwater ecosystems worldwide. Physical alteration, habitat loss, water withdrawal, pollution, overexploitation and the introduction of non-native species all contribute to the decline in freshwater species. Today, freshwater species are, in general, at higher risk of extinction than those in forests, grasslands and coastal ecosystems. For North America alone, the projected extinction rate for freshwater fauna is five times greater than that for terrestrial fauna--a rate comparable to the species loss in tropical rainforest. Because many of these extinctions go unseen, the level of assessment and knowledge of the status and trends of freshwater species are still very poor, with species going extinct before they are even taxonomically classified. Increasing human population growth and achieving the sustainable development targets set forth in 2002 will place even higher demands on the already stressed freshwater ecosystems, unless an integrated approach to managing water for people and ecosystems is implemented by a broad constituency. To inform and implement policies that support an integrated approach to water management, as well as to measure progress in halting the rapid decline in freshwater species, basin-level indicators describing the condition and threats to freshwater ecosystems and species are required. This paper discusses the extent and quality of data available on the number and size of populations of freshwater species, as well as the change in the extent and condition of natural freshwater habitats. The paper presents indicators that can be applied at multiple scales, highlighting the usefulness of using remote sensing and geographical information systems technologies to fill some of the existing information gaps. Finally, the paper includes an analysis of major data gaps and information needs with respect to freshwater species to measure progress towards the 2010 biodiversity targets.

Distal margin requirements after preoperative chemoradiotherapy for distal rectal carcinomas: are < or = 1 cm distal margins sufficient?

BACKGROUND: Sphincter-sparing alternatives to abdominoperineal resection (APR) in the treatment of rectal cancer often are underused out of concern for inadequate distal margins and local failure. The present study addresses whether sphincter-sparing techniques with distal margins < or = 1 cm adversely influence oncological outcome in patients given preoperative chemoradiotherapy. METHODS: Thirty-seven patients with rectal cancer < or = 8 cm from the anal verge were enrolled in the study. Preoperative external beam radiotherapy (5400 Gy) was administered together with continuous infusion of 5-fluorouracil (300 mg/m2/day). Surgical resection was performed in 36 patients with pathological assessment of tumor response and margins. Patients with sphincter-sparing resection and distal margins > 1 cm or < or = 1 cm and those who underwent APR were compared. RESULTS: Thirty-six patients completed preoperative chemoradiotherapy, with successful sphincter-preservation in 28 patients. At a median follow-up of 33 months, there were 12 recurrences overall, which included 11 distant failures and four pelvic failures. Disease-free survival (DFS) was not different between those who had an APR compared with sphincter-sparing resection with distal margins < or = 1 cm. DFS was worse (P < .02) when radial margins were < or = 3 mm compared with > 3 mm. CONCLUSIONS: Sphincter preservation is feasible in more than 75% of patients with tumors < or = 8 cm from the anal verge after preoperative chemoradiotherapy. Sphincter-sparing surgery with distal margins < or = 1 cm can be used without adversely influencing local recurrence or DFS. Limited radial margins (< or = 3 mm), however, are associated with increased disease recurrence.

Treatment of resectable and locally advanced pancreatic cancer.

BACKGROUND: Pancreatic cancer is the fifth leading cause of cancer death in the United States, with an overall 5-year survival rate of less than 5%. A minority of patients are candidates for surgical resection, but most treatment strategies focus on palliative care. METHODS: We discuss strategies in the diagnosis and treatment of resectable and locally advanced pancreatic cancer by reviewing available phase II and phase III trials, as well as large retrospective studies. RESULTS: Surgical resection for pancreatic cancer is done today with an operative mortality rate below 5% and a 5-year survival rate of approximately 25%. There is evidence that chemoradiation may improve survival and quality of life in both the adjuvant setting and for locally advanced disease. Operative, minimally invasive, and endoscopic techniques are successful in palliating pain and jaundice. CONCLUSIONS: The diagnosis and treatment of pancreatic cancer continue to improve although most patients will succumb to their disease. Novel methods of earlier detection and more effective systemic therapies are needed to significantly improve outcomes.

Adjuvant therapy of resected adenocarcinoma of the pancreas.

Seventy-two patients underwent resections of pancreatic carcinomas between 1981 and 1989 at the Hospital of the University of Pennsylvania and were evaluable for follow-up. There were three treatment groups as treatment policies evolved. Initially, patients were observed after surgery without adjuvant treatment (Group 1-33 patients). Beginning in 1984, patients were offered adjuvant radiation therapy postoperatively (Group 2-19 patients) and eight of these patients also received 5-FU as an IV bolus on the first 3 days of the first and fifth weeks of treatment. Twenty patients were treated with chemosensitized radiation therapy following surgery using 96-hour 5-FU infusions during the first and fifth weeks of treatment. There were four postoperative deaths, which are excluded from the analysis, and sites of failure could not be determined for five other patients. Among evaluable patients, local recurrences occurred in 85% of the patients in group 1, 55% of the patients in group 2, and 25% of the patients in group 3. The 2-year survival was 35% in group 1, 30% in group 2, and 43% in group 3. Patients with involved surgical margins had a poor survival; only 2 of these 16 patients survived longer than 18 months. Among patients with negative margins, the 2-year survival is 41% in group 1, 33% in group 2, and 59% in group 3. Although the number of patients is smaller, the 3-year survival is 22% in group 1, 11% in group 2, and 47% in group 3. Chemosensitized irradiation is well tolerated in these patients. The major challenge in this group of patients is nutritional maintenance. There was no other significant toxicity. The trend in these observations suggests that survival following pancreatic resection is substantially improved with the addition of adjuvant chemosensitized radiation therapy.

The use of T2 distribution to study tumor extent and heterogeneity in head and neck cancer.

Demarcation of the extent of malignant tissue is essential for planning a course of radiotherapy. MR images may provide additional information for delineating the target volume because of the large difference in the proton magnetic resonance relaxation times between normal and malignant tissues. In 13 patients with head and neck tumors the distribution of the proton spin-spin relaxation times, T2, at 1.5 Tesla were evaluated throughout the physician designated target volume and normal surrounding tissue. The T2 values within the tumor were always elevated compared with normal tissue, the highest values being in the nominal center of the tumor and decreasing toward the periphery. The regional distribution of T2 values within the tumor is a measure of the tissue heterogeneity within the tumor volume. In addition, the large differences in T2 relaxation times between normal and disease tissues were used in a computer algorithm to automatically demarcate the boundary of abnormal tissue in each axial MRI section. This potentially could significantly expedite the time required to identify the target volume on multiple sections and thus remove one of the major time constraints for 3D treatment planning.