Non-randomness of the anatomical distribution of tumors

Background: Why does a tumor start where it does within an organ? Location is traditionally viewed as a random event, yet the statistics of the location of tumors argues against this being a random occurrence. There are numerous examples including that of breast cancer. More than half of invasive breast cancer tumors start in the upper outer quadrant of the breast near the armpit, even though it is estimated that only 35 to 40% of breast tissue is in this quadrant. This suggests that there is an unknown microenvironmental factor that significantly increases the risk of cancer in a spatial manner and that is not solely due to genes or toxins. We hypothesize that tumors are more prone to form in healthy tissue at microvascular ‘hot spots’ where there is a high local concentration of microvessels providing an increased blood flow that ensures an ample supply of oxygen, nutrients, and receptors for growth factors that promote the generation of new blood vessels. Results: To show the plausibility of our hypothesis, we calculated the fractional probability that there is at least one microvascular hot spot in each region of the breast assuming a Poisson distribution of microvessels in two-dimensional cross sections of breast tissue. We modulated the microvessel density in various regions of the breast according to the total hemoglobin concentration measured by near infrared diffuse optical spectroscopy in different regions of the breast. Defining a hot spot to be a circle of radius 200 μm with at least 5 microvessels, and using a previously measured mean microvessel density of 1 microvessel/mm2, we find good agreement of the fractional probability of at least one hot spot in different regions of the breast with the observed invasive tumor occurrence. However, there is no reason to believe that the microvascular distribution obeys a Poisson distribution. Conclusions: The spatial location of a tumor in an organ is not entirely random, indicating an unknown risk factor. Much work needs to be done to understand why a tumor occurs where it does. Electronic supplementary material The online version of this article (10.1186/s41236-017-0006-7) contains supplementary material, which is available to authorized users

Plastias de estenoses de intestino delgado na doença de Crohn: resultados imediatos e tardios Crohn’s disease small bowel strictureplasties: early and late results

RACIONAL: As enteroplastias constituem alternativa cirúrgica no tratamento da estenose da doença de Crohn. OBJETIVO: Analisar, retrospectivamente, a evolução precoce e tardia do tratamento cirúrgico das estenoses do intestino delgado, segmento ileocecal ou anastomose ileocólica secundária à doença de Crohn, com emprego de plastias intestinais. MÉTODOS: Foram estudados 28 doentes, operados entre setembro de 1991 e maio de 2004, com seguimento médio pós-operatório de 58,1 meses. Dezesseis (57,1%) eram do sexo masculino, com média etária de 33,3 anos, e 13 doentes (46,4%) apresentavam ressecções intestinais prévias. Foram realizadas 116 plastias, sendo 94 (81%) à Heineke-Mikulicz, 15 (13%) do tipo Finney e 7 (6%) ileocoloplastias látero-laterais. Em 18 doentes (64,3%) realizaram-se ressecções intestinais concomitantes. RESULTADOS: Verificaram-se 14 complicações em 7 doentes (25%) e um óbito (3,6%), secundário a complicações pulmonares após reoperações por sangramento intestinal da anastomose êntero-entérica. Ocorreram duas complicações gerais (14,3%), em dois doentes (7,1%) e oito complicações locais precoces (57,1%), em sete doentes (25%), sendo a mais freqüente deiscência de plastia, em três casos (10,7%). Complicações locais tardias ocorreram em dois doentes (7,1%), ambos com hérnia incisional e fístula êntero-cutânea. Recidiva sintomática da estenose ocorreu em 17 doentes (63%) e 2 deles (7,4%), apresentaram fístulas êntero-cutâneas, sendo o índice de reoperação de 40,7%. Observaram-se quatro recidivas (3,5%), em três doentes (11,1%) em local de plastia prévia, sendo mais comum no tipo Finney (20%). CONCLUSÃO: As plastias apresentaram baixos índices de complicações e propiciam alívio dos sintomas. Uma vez que muitos doentes com doença de Crohn necessitarão de várias cirurgias ao longo da vida, as plastias intestinais constituem alternativas eficazes, com resolução dos sintomas obstrutivos, evitando-se ressecções intestinais extensas e suas conseqüências.<br>BACKGROUND: Strictureplasty is an alternative surgical procedure for Crohn’s disease, particulary in patients with previous resections or many intestinal stenosis. AIM: To analyze surgical complications and clinical follow-up in patients submitted to strictureplasty secondary to Crohn’s disease. METHODS: Twenty-eight patients (57.1% male, mean age 33.3 years, range 16-54 years) with Crohn’s disease and intestinal stenosis (small bowel, ileocecal region and ileocolic anastomosis) were submitted to strictureplasty, at one institution, between September 1991 and May 2004. Thirteen patients had previous intestinal resections. The mean follow-up was 58.1 months. A total of 116 strictureplasties were done (94 Heineke-Mikulicz - 81%, 15 Finney - 13%, seven side-to-side ileocolic strictureplasty - 6%). Three patients were submitted to strictureplasty at two different surgical procedures and two in three procedures. RESULTS: Regarding to strictureplasty, postoperative complication rate was 25% and mortality was 3.6%. Early local complication rate was 57.1%, with three suture leaks (10.7%) and late complication was present in two patients, both with incisional hernial and enterocutaneous fistulas (28.6%). Patients remained hospitalized during a medium time of 12.4 days. Clinical and surgical recurrence rates were 63% and 41%, respectively. Among the patients submitted to another surgery, two patients had two more operations and one had three. Recurrence rate at strictureplasty site was observed in 3.5%, being Finney technique the commonest one. Presently, 19 patients had been asymptomatic with the majority of them under medical therapy. CONCLUSION: Strictureplasties have low complication rates, in spite of having been done at compromised site, with long term pain relief. Considering the clinical course of Crohn’s disease, with many patients being submitted to intestinal resections, strictureplasties should be considered as an effective surgical treatment to spare long intestinal resections