Modern criteria to establish human cancer etiology.

The Cancer Etiology Branch of the National Cancer Institute hosted a workshop, "Validation of a causal relationship: criteria to establish etiology," to determine whether recent technological advances now make it possible to delineate improved or novel criteria for the rapid establishment for cancer causation. The workshop was held in Washington, D.C., December 11-12, 2003, and participants were among the international leaders in the fields of epidemiology, chemistry, biochemistry, microbiology, virology, environmental and chemical carcinogenesis, immunology, pathology, molecular pathology, genetics, oncology, and surgical oncology. There was a general consensus that the rapid identification of human carcinogens and their removal (when possible) or the establishment of specific preventive and therapeutic measures was the most desirable and effective way to have a rapid and positive impact in the fight against cancer. From a clinical perspective, it may be as important to target initiators, cocarcinogens and promoters, if by removing any one of them tumor growth can be prevented. Future studies should focus on interactions among and between different biological, chemical, and physical agents. Analyses of single agents can at times miss their carcinogenic potential when such agents are carcinogenic only in subgroups of individuals because of their genetic background, diet, exposure to other carcinogens, or microbial infection. Epidemiology, molecular pathology (including chemistry, biochemistry, molecular biology, molecular virology, molecular genetics, epigenetics, genomics, proteomics, and other molecular-based approaches), and animal and tissue culture experiments should all be seen as important integrating evidence in the determination of human carcinogenicity. Concerning the respective roles of epidemiology and molecular pathology, it was noted that epidemiology allows the determination of the overall effect of a given carcinogen in the human population (e.g., hepatitis B virus and hepatocellular carcinoma) but cannot prove causality in the individual tumor patient. Molecular pathology cannot determine the overall impact of a carcinogen in the population but can at times prove causality in the individual tumor patient [such as the detection of high-risk human papillomavirus (HPV) in a cervical carcinoma biopsy]. This is possible when molecular techniques have shown that the agent is required for transformation or malignant growth of human cells (such as antisense HPV strategies showing the requirement for the expression of HPV proteins for tumor cell growth) and when there is supportive experimental animal evidence. Ideally, epidemiology and molecular pathology information together with experimental evidence in animals should be available for the most reliable identification of human carcinogens. All sets of data are not always available, and a rapid identification of human carcinogens is in the best public health interest. Swift validation of a causal relationship when followed by a rapid deployment of preventive and therapeutic approaches should lead to a favorable public health impact (such as hepatitis B virus vaccination to prevent hepatocellular carcinoma).

Visualization of the epigastric vessels and bladder before laparoscopic trocar placement.

OBJECTIVE: Transillumination and laparoscopic visualization are two techniques recommended to minimize the risks of injury to abdominal wall structures during insertion of secondary trocars. This study was designed to determine the effectiveness of these techniques to locate the epigastric vessels and superior bladder margin. DESIGN: Prospective observational. SETTING: Academic medical centers. PATIENT(S): One hundred five women undergoing laparoscopy for tubal sterilization, infertility, pelvic masses, or pelvic pain. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): The ability to visualize the superficial and inferior epigastric vessels, and bladder margin; body mass index (BMI; in kilograms per meter squared); and skin color. RESULT(S): Transillumination successfully visualized 64% of superficial epigastric vessels and was less effective both as weight increased (BMI <25 kg/m(2): 86%; BMI = 25-30 kg/m(2): 61%; BMI >30 kg/m(2): 25%) and in dark-skinned women (69%) compared to those with lighter skin (42%). Laparoscopic visualization successfully identified 82% of inferior epigastric vessels and 46% of bladder margins, and was less effective as weight increased. CONCLUSION(S): Transillumination can successfully locate superficial epigastric vessels, and laparoscopic visualization can locate inferior epigastric vessels and the superior bladder margin in the majority of women undergoing laparoscopy. Transillumination is less effective in dark-skinned women, and both techniques are less effective with increasing body weight.

Patient rotation and resolution of unilateral cornual obstruction during hysterosalpingography.

OBJECTIVE: Unilateral obstruction of the proximal fallopian tube is identified in 10-24% of patients undergoing hysterosalpingography for evaluation of infertility. Upon further testing, this obstruction spontaneously resolves 16-80% of the time. We hypothesized that patient rotation during hysterosalpingography might resolve proximal tubal obstruction in some cases by altering either the location of intrauterine air bubbles or the spatial relationship of the tube to the uterine fundus. METHODS: In patients in whom unilateral proximal tubal obstruction was detected during hysterosalpingography performed for standard clinical indications, the patient was rotated on her hip approximately 45 degrees such that the obstructed tube was first superior (ventral) to the patent tube, and dye was reinjected. If obstruction did not resolve, the patient was rotated in the opposite direction so that the obstructed tube was inferior (dorsal) to the patent tube and dye reinjected. RESULTS: Unilateral tubal obstruction was found in 15% of cases (24 of 156). Rotating the patient with obstructed tube superior to the patent tube never resulted in tubal patency, whereas rotating the patient with the obstructed tube inferior resulted in resolution of tubal patency in 63% of cases (15 of 24) CONCLUSION: . Unilateral cornual obstruction during hysterosalpingography is often resolved by rotating the patient such that the obstructed tube is more inferior. Although this observation may be the result of dislodging smaller air bubbles, from a fluid dynamics perspective a more likely explanation is unkinking of the more inferior tube.