Can physical trauma cause breast cancer?

Association of Trauma With Long-Term Risk of Death and Immune-Mediated or Cancer Disease in Same-Sex Twins

Importance

Immediate consequences of trauma include a rapid and immense activation of the immune system, whereas long-term outcomes include premature death, physical disability, and reduced workability.

Objective

To investigate if moderate to severe trauma is associated with long-term increased risk of death or immune-mediated or cancer disease.

Design, Setting, and Participants

This registry-based, matched, co-twin control cohort study linked the Danish Twin Registry and the Danish National Patient Registry to identify twin pairs in which 1 twin had been exposed to severe trauma and the other twin had not from 1994 to 2018. The co-twin control design allowed for matching on genetic and environmental factors shared within twin pairs.

Exposure

Twin pairs were included if 1 twin had been exposed to moderate to severe trauma and the other twin had not (ie, co-twin). Only twin pairs where both twins were alive 6 months after the trauma event were included.

Main Outcome and Measure

Twin pairs were followed up from 6 months after trauma until 1 twin experienced the primary composite outcome of death or 1 of 24 predefined immune-mediated or cancer diseases or end of follow-up. Cox proportional hazards regression was used for intrapair analyses of the association between trauma and the primary outcome.

Results

A total of 3776 twin pairs were included, and 2290 (61%) were disease free prior to outcome analysis and were eligible for the analysis of the primary outcome. The median (IQR) age was 36.4 (25.7-50.2) years. The median (IQR) follow-up time was 8.6 (3.8-14.5) years. Overall, 1268 twin pairs (55%) reached the primary outcome; the twin exposed to trauma was first to experience the outcome in 724 pairs (32%), whereas the co-twin was first in 544 pairs (24%). The hazard ratio for reaching the composite outcome was 1.33 (95% CI, 1.19-1.49) for twins exposed to trauma. Analyses of death or immune-mediated or cancer disease as separate outcomes provided hazard ratios of 1.91 (95% CI, 1.68-2.18) and 1.28 (95% CI, 1.14-1.44), respectively.

Conclusion and Relevance

In this study, twins exposed to moderate to severe trauma had significantly increased risk of death or immune-mediated or cancer disease several years after trauma compared with their co-twins.

Changes to breast structure and function across a woman's lifespan: Implications for managing and modeling female breast injuries

BACKGROUND

Female breasts change throughout a woman's life in response to fluctuating hormonal influences. Individuals managing active women and those modeling female breasts must understand these structural and functional changes across a female's lifespan because these changes affect breast injuries sustained by women.

METHODS

We initially review female breast structure and function and then describe how breast structure changes across a woman's lifespan. Key studies about direct contact and frictional breast injuries are then summarized. Limitations of current breast injury research, gaps in knowledge about breast injuries incurred by specific populations, and the lack of breast injury models are also highlighted.

FINDINGS

With minimal anatomical protection, it is unsurprising that breast injuries occur. Although research about breast injuries is scant, direct contact during blunt force trauma to the anterior chest wall and frictional breast injuries have been reported. There is a lack, however, of research documenting the incidence and severity of breast injuries incurred in occupational settings and in women's sports. Therefore, to design effective breast protective equipment, we recommend research to model and investigate the mechanisms and forces involved in breast injuries, particularly injuries sustained during sport.

INTERPRETATION

This unique review summarizes how female breasts change over a woman's life span, with implications for breast injuries sustained by females. Knowledge gaps about female breast injuries are highlighted. We conclude by recommending research required to develop evidence-based strategies to improve how we classify, prevent, and clinically manage breast injuries sustained by females.

SUMMARY

We review changes to the breast across a woman's lifespan, highlighting implications for managing and modeling female breast injuries.

Computational and In Vitro Approaches to Elucidate the Anti-cancer Effects of Arnica montana in Hormone-Dependent Breast Cancer

BACKGROUND

 Breast cancer is the most common cancer in women worldwide. Use of homeopathic medicines for the treatment of cancers has increased in the last several years. Arnica montana is an anti-inflammatory homeopathic medicine used in traumatic conditions and because of this property we performed investigations for its potential as a chemotherapeutic agent against breast cancer.

METHODS

 An ethanolic extract of Arnica montana (mother tincture, MT), prepared according to the Homoeopathic Pharmacopoeia of India, was characterized by gas chromatography-mass spectroscopy (GC-MS), followed by computational (in silico) analysis using molecular docking, to identify specific compounds that can bind and modulate the activity of key proteins involved in breast cancer survival and progression. To validate the in silico findings, in a controlled experiment breast cancer cells (MCF7) were treated in vitro with Arnica montana and the cytotoxic effects assessed by flowcytometry, fluorescence microscopy, scratch assay, clonogenic potential and gene expression analysis.

RESULTS

 Phytochemical characterization of ethanolic extract of Arn MT by GC-MS allowed identification of several compounds. Caryophyllene oxide and 7-hydroxycadalene were selected for molecular docking studies, based on their potential drug-like properties. These compounds displayed selective binding affinity to some of the recognized target proteins of breast cancer, which included estrogen receptor alpha (ERα), progesterone receptor (PR), epidermal growth factor receptor (EGFR), mTOR (mechanistic target of rapamycin) and E-cadherin. In vitro studies revealed induction of apoptosis in MCF7 cells following treatment with Arn MT. Furthermore, treatment with Arn MT revealed its ability to inhibit migration and colony forming abilities of the cancer cells.

CONCLUSION

 Considering the apoptotic and anti-migratory effects of Arnica montana in breast cancer cells in vitro, there is a need for this medicine to be further validated in an in vivo model.

Awareness levels of breast cancer among female university and medical college students in Sylhet city of Bangladesh

BACKGROUND

Breast cancer has become a concerning health problem worldwide due to its increasing incidence rate. Women from developing countries are dying off due to the lack of knowledge on breast cancer and its different early detection programs.

AIMS

This study explores the level of knowledge about breast cancer risk factors, early warning signs, screening, and therapeutic approaches and their influential determinants among university and medical college students.

METHODS

A cross-sectional study was conducted, including 567 female university-level students (343 female students from 1 university and 224 female students from 1 medical college). This study used a semi-structured questionnaire about four aspects (risk factors, early warning signs, screening, and therapeutic approaches) of breast cancer, latent class analysis (LCA), and latent class regression (LCR) for investigation.

RESULTS

The percent of knowing correct answers of risk factors, early warning signs, screening approaches, and therapeutic methods were 86.3%, 69.8%, 70.2%, and 51.2%, respectively for medical students who had a high level of awareness and those for university students were 73.0%, 66.8%, 35.9%, and 24.7%. On the other hand, only 37.95% of medical students had been practicing Breast self-examination (BSE), while it was 18.37% for university students. The most effective predictors of the high level of awareness were age, advertisements (ad) promoting awareness about breast cancer, programs/campaign related to breast cancer, and personal breast problem history.

CONCLUSIONS

Taken together, the awareness level about four aspects of breast cancer is low among university students and is moderately high among medical students. Therefore, relevant health education programs in every educational institute are urgently needed to improve the awareness levels among female students to improve women's health at home and abroad.

Systematic review of the epidemiology of a single physical trauma and cancer

Background

A systematic review of single physical trauma and cancer was carried out, with a meta-analysis where deemed appropriate.

Methods

A comprehensive search of the literature including databases such as Medline and Embase identified 1529 potentially relevant papers for inclusion. A further 89 potentially relevant studies were identified from bibliographies. After review of titles and abstracts and then full papers, a total of 77 studies were included in the broader review of trauma and cancer, and 31 of these studies considered single physical trauma and cancer. The searches were carried out in June 2016.

Results

Although physical trauma as a cause of cancer has been an issue of clinical interest for decades, the epidemiological evidence was sparse. Only for traumatic brain injury and brain cancer was there considered a sufficient number of epidemiological studies for a meta-analysis. A random effects meta-relative risk for glioma from cohort studies was 0.96 (95% CI: 0.49 to 1.88) and 1.53 (95% CI: 1.02 to 2.27) for case-control studies. The equivalent results for meningioma were 1.22 (95% CI: 0.85 to 1.76) and 1.88 (95% CI: 0.84 to 1.49) respectively.

Conclusions

Further work is required to clarify whether physical trauma has a role in cancer development, perhaps by exploiting trauma registries.

Breast cancer screening knowledge among Hungarian women: a cross-sectional study

Background

Breast cancer (BC) is the leading malignant tumor among women worldwide. Although attending regular BC screening effectively reduces cancer-related mortality, surveys testify that screening knowledge is critically low among women. We aimed to conduct a comparative cross-sectional survey to assess BC and BC screening-related knowledge in Hungary.

Methods

Women between 25 and 65 years of age without a previous history of malignant tumors were included with non-probability sampling in 2017. Respondents were recruited either from primary care (laywomen) or from the waiting rooms of mammography (screening attendees). A self-completion questionnaire was constructed with questions about BC (risk factors, signs and symptoms, curability, and mortality), BC screening (mammography and breast self-examination), and BC-related information sources to assess knowledge among laywomen and screening attendees. In addition to descriptive statistics, odds ratios with 95% confidence intervals were calculated in univariate analysis and logistic regression was used in multivariate analysis.

Results

Altogether, 480 women completed the questionnaire, of which 429 (227 laywomen and 202 screening attendees) were eligible for inclusion. Laywomen and screening attendees knew the recommended age at first mammography in 35.2% and 86.6%, the recommended frequency of screening in 33.9% and 12.9%, the recommended age at first breast-self examination in 38.8% and 51.2%, had sufficient knowledge of the risk factors of BC in 7.0% and 5.9%, and that of signs and symptoms of BC in 16.7% and 28.9%, respectively. A higher proportion of screening attendees correctly identified the recommended age of first BC screening correctly than that of laywomen (86.6% vs. 35.2%; p < 0.001). The most popular information sources were television among laywomen and general practitioners or specialists among screening attendees. In multivariate analysis, older age, higher education, and place of residency were significant predictors of the right answers.

Conclusions

Although knowledge was insufficient in almost all fields of the questionnaire, the most prominent gap was observed concerning risk factors and signs and symptoms of BC both in laywomen and, unexpectedly, screening attendees. Most laywomen were lacking knowledge of screening protocol. These results urge breast health and BC knowledge interventions in Hungary.

Supplementary information

The online version contains supplementary material available at 10.1186/s12905-021-01204-9.

Chronic physical health conditions and associated factors among people with serious orthopaedic injuries: A systematic review

Introduction

A clear understanding of the development of chronic physical health conditions following orthopaedic injury is essential to fully recognise the magnitude and burden of injury, improve treatment and predict certain outcomes. This review aimed at systematically identifying and evaluating current evidence of the incidence and prevalence of chronic physical health conditions and factors associated with chronic physical health conditions following serious orthopaedic injury.

Materials and method

Systematic literature search was performed using Ovid MEDLINE, Scopus, and Embase via Ovid, Cochrane Library and Ovid Emcare up to 30 December 2018. Observational studies relating to the incidence or prevalence of chronic physical health conditions and associated factors in people with serious orthopaedic injuries were included. Data extraction and methodological quality assessment were carried out independently by 2 reviewers.

Result

Of the 4835 references identified in the initial search, only five studies with sample sizes ranging from 83 to 3846 met the criteria for inclusion. The most prevalent conditions reported in people with serious orthopaedic injury included coronary artery disease, arrhythmias, myocardial infarction, hypertension, diabetes mellitus and chronic heart failure. Bronchial, rectal, prostate and breast cancers were also causes of late death in orthopaedic injury survivors. Most of the studies included in this review were unable to determine whether these conditions were related to injuries.

Conclusions

Chronic physical health conditions are prevalent among people with serious orthopaedic injury. Little is known about factors associated with chronic physical health conditions following serious orthopaedic injury or whether physical health conditions are associated with injury. Further work needs to be done to identify causal pathways and the longer-term effects of orthopaedic injury on the risk of developing chronic physical health conditions.

Risk factors for inflammatory and non-inflammatory breast cancer in North Africa

PURPOSE

Studies of the etiology of inflammatory breast cancer (IBC), a rare but aggressive breast cancer, have been hampered by limited risk factor information. We extend previous studies by evaluating a broader range of risk factors.

METHODS

Between 2009 and 2015, we conducted a case-control study of IBC at six centers in Egypt, Tunisia, and Morocco; enrolled were 267 IBC cases and for comparison 274 non-IBC cases and 275 controls, both matched on age and geographic area to the IBC cases. We administered questionnaires and collected anthropometric measurements for all study subjects. We used multiple imputation methods to account for missing values and calculated odds ratios (ORs) and 95% confidence intervals (CIs) using polytomous logistic regression comparing each of the two case groups to the controls, with statistical tests for the difference between the coefficients for the two case groups.

RESULTS

After multivariable adjustment, a livebirth within the previous 2 years (OR 4.6; 95% CI 1.8 to 11.7) and diabetes (OR 1.8; 95% CI 1.1 to 3.0) were associated with increased risk of IBC, but not non-IBC (OR 0.9; 95% CI 0.3 to 2.5 and OR 0.9; 95% CI 0.5 to 1.6 for livebirth and diabetes, respectively). A family history of breast cancer, inflammatory-like breast problems, breast trauma, and low socioeconomic status were associated with increased risk of both tumor types.

CONCLUSIONS

We identified novel risk factors for IBC and non-IBC, some of which preferentially increased risk of IBC compared to non-IBC. Upon confirmation, these findings could help illuminate the etiology and aid in prevention of this aggressive cancer.

Hypothesis: Bacterial induced inflammation disrupts the orderly progression of the stem cell hierarchy and has a role in the pathogenesis of breast cancer

BACKGROUND

The hierarchical model of stem cell genesis is based on the idea that the number of cell divisions between the zygote and fully differentiated epithelial cells is kept close to the minimum, which is log to the base 2 of the total number of cells produced in a human lifetime. The model assumes the orderly progression of stem cell divisions requires precise control at every stage in development. If the orderly progression is maintained then cancer will be rare. A prediction of the model is that if the orderly progression of the stem cell hierarchy is disturbed by trauma, ulceration or inflammation then cancer will occur.

HYPOTHESIS

Bacterial induced inflammation in breast ducts disturbs the stem cell hierarchy and is a cause of breast cancer.

EVIDENCE

Mammalian milk is not sterile. It contains a range of bacteria, derived endogenously by the entero-mammary circulation. The dominant flora consists of lactose fermenting bacteria. Pregnancy and breast feeding reduce the risk of subsequent breast cancer. The implication is that a lactose fermenting bacterial flora in breast ducts is protective. Malignant and benign breast tissue contains bacteria derived endogenously, but studies so far have not revealed a specific flora associated with malignancy. Periodontitis is associated with oral, oesophageal, colonic, pancreatic, prostatic and breast cancer. The pathogenic bacteria which cause periodontitis spread endogenously to cause inflammation at other epithelial sites. Meta-analysis of epidemiological studies shows that the consumption of yoghurt is associated with a reduction in the risk of breast cancer.

CONCLUSION

The hypothesis, although not proven, is supported by the available evidence. Lactose fermenting bacteria protect but pathogenic bacteria which induce inflammation raise the risk of breast cancer. The consumption of yoghurt also appears to be protective.

Tumour Initiation: a Discussion on Evidence for a "Load-Trigger" Mechanism

Appropriate mechanical forces on cells are vital for normal cell behaviour and this review discusses the possibility that tumour initiation depends partly on the disruption of the normal physical architecture of the extracellular matrix (ECM) around a cell. The alterations that occur thence promote oncogene expression. Some questions, that are not answered with certainty by current consensus mechanisms of tumourigenesis, are elegantly explained by the triggering of tumours being a property of the physical characteristics of the ECM, which is operative following loading of the tumour initiation process with a relevant gene variant. Clinical observations are consistent with this alternative hypothesis which is derived from studies that have, together, accumulated an extensive variety of data incorporating biochemical, genetic and clinical findings. Thus, this review provides support for the view that the ECM may have an executive function in induction of a tumour. Overall, reported observations suggest that either restoring an ECM associated with homeostasis or targeting the related signal transduction mechanisms may possibly be utilised to modify or control the early progression of cancers. The review provides a coherent template for discussing the notion, in the context of contemporary knowledge, that tumourigenesis is an alliance of biochemistry, genetics and biophysics, in which the physical architecture of the ECM may be a fundamental component. For more definitive clarification of the concept there needs to be a phalanx of experiments conceived around direct questions that are raised by this paper.

Preliminary Results of a New Auxiliary Mechatronic Near-Field Radar System to 3D Mammography for Early Detection of Breast Cancer

Accurate and early detection of breast cancer is of high importance, as it is directly associated with the patients’ overall well-being during treatment and their chances of survival. Uncertainties in current breast imaging methods can potentially cause two main problems: (1) missing newly formed or small tumors; and (2) false alarms, which could be a source of stress for patients. A recent study at the Massachusetts General Hospital (MGH) indicates that using Digital Breast Tomosynthesis (DBT) can reduce the number of false alarms, when compared to conventional mammography. Despite the image quality enhancement DBT provides, the accurate detection of cancerous masses is still limited by low radiological contrast (about 1%) between the fibro-glandular tissue and affected tissue at X-ray frequencies. In a lower frequency region, at microwave frequencies, the contrast is comparatively higher (about 10%) between the aforementioned tissues; yet, microwave imaging suffers from low spatial resolution. This work reviews conventional X-ray breast imaging and describes the preliminary results of a novel near-field radar imaging mechatronic system (NRIMS) that can be fused with the DBT, in a co-registered fashion, to combine the advantages of both modalities. The NRIMS consists of two antipodal Vivaldi antennas, an XY positioner, and an ethanol container, all of which are particularly designed based on the DBT physical specifications. In this paper, the independent performance of the NRIMS is assessed by (1) imaging a bearing ball immersed in sunflower oil and (2) computing the heat Specific Absorption Rate (SAR) due to the electromagnetic power transmitted into the breast. The preliminary results demonstrate that the system is capable of generating images of the ball. Furthermore, the SAR results show that the system complies with the standards set for human trials. As a result, a configuration based on this design might be suitable for use in realistic clinical applications.

Breast Injuries in Female Collegiate Basketball, Soccer, Softball and Volleyball Athletes: Prevalence, Type and Impact on Sports Participation

Objective

In 2015-2016, over 214,000 female athletes competed at the collegiate level in the United States (U.S.). The National Collegiate Athletic Association (NCAA) collects injury data; however, breast-related injuries do not have a specific reporting category. The exact sequelae of breast injury are unknown; however, a relationship between breast injury and fat necrosis, which mimics breast carcinoma, is documented outside of sports participation. Breast injuries related to motor vehicle collisions, seatbelt trauma, and blunt trauma have been reported. For these reasons, it is important to investigate female breast injuries in collegiate sports. The objectives of this study are to report the prevalence of self-reported breast injuries in female collegiate athletes, explore injury types and treatments, and investigate breast injury reporting and impact on sports participation.

Materials and Methods

A cross-sectional study of female collegiate athletes at four U.S. universities participating in basketball, soccer, softball, or volleyball. Main outcome measure was a questionnaire regarding breast injuries during sports participation.

Results

Almost half of the 194 participants (47.9%) reported a breast injury during their collegiate career, less than 10% reported their injury to health personnel with 2.1% receiving treatment. Breast injuries reported by breast injuries reported by sport include softball (59.5%), basketball (48.8%), soccer (46.7%), and volleyball (34.6%).

Conclusions

The long-term effects and sequelae of breast injuries reported by female collegiate athletes during sport play are unknown. Nearly 50% of participants had a breast injury during sports activities. Although 18.2% indicated that breast injury affected sports participation, only 9.6% of the injuries were reported to medical personnel with 2.1% receiving treatment.

Clinical Presentation and Frequency of Risk Factors in Patients with Breast Carcinoma in Pakistan

BACKGROUND

Breast cancer is known to be one of the most prevalent cancers among women in both developing and developed countries .The incidence of breast cancer in Pakistan has increased dramatically within the last few years and is the second country after Israel in Asia to have highest proportional cases of breast cancer. However, there are limited data for breast cancer available in the literature from Pakistan.

OBJECTIVES

The study was conducted to bring to light the common clinical presentation of breast cancer and to evaluate the frequency of established risk factors in breast carcinoma patients and furthermore to compare the findings between premenopausal and postmenopausal women in Pakistan.

MATERIALS AND METHODS

A 6 months (from July 2012 to Dec 2012) cross sectional survey was conducted in Surgical and Oncology Units of Civil Hospital, Karachi. Data were collected though a well developed questionnaire from 105 female patients diagnosed with carcinoma of breast and analyzed using SPSS version 17. Institutional ethical approval was obtained prior to data collection.

RESULTS

Out of 105 patients, 43 were premenopausal and 62 were postmenopausal, 99 being married. Mean age at diagnosis was 47.8 ± 12.4 years. A painless lump was the most frequent symptom, notived by 77.1%(n=81). Some 55.2% (n=58) patients had a lump in the right breast and 44.8%(n=47) in the left breast. In the majority of cases, the lump was present in upper outer quadrant 41.9% (n=44). Mean period of delay from appearance of symptoms to consulting a doctor was 5.13 ± 4.8 months, from the shortest 1 month to the longest 36 months. Long delay (> 3 months) was the most frequent figure 41.9%. Considering overall risk factors most frequent were first pregnancy after 20 years of age (41%), physical breast trauma (28.6%), lack of breast feeding(21.9%), and early menarche <11 years (19%), followed by null parity (16.2%), consumption of high fat diet (15.2%), family history of breast cancer or any other cancer in first degree relatives (9.5% and 13.3%, respectively). Some of the less common factors were late menopause >54 years (8.6%), use of oral contraceptive pills (10.5%), use of hormone replacement therapy (4.7%),smoking (4.7%) and radiation (0.96%). Significant differences (p<0.005) were observed between pre and post menopausal women regarding history of physical breast trauma, practice of breast feeding and parity.

CONCLUSIONS

A painless lump was the most frequent clinical presentation noted. Overall age at first child > 20 years, physical breast trauma, lack of breast feeding ,early menarche <11 were the most frequent risk factors. Physical breast trauma, lower parity, a trend for less breast feeding had more significant associations with pre-menopausal than post-menopausal onset. Increase opportunity of disease prevention can be obtained through better understanding of clinical presentation and risk factors important in the etiology of breast cancer.

Potential Safety Loophole of Fat Grafting in Breast Cancer Patients

Autologous fat grafting (AFG) accounts for 9.1 % of all cosmetic surgical procedures in the world. Its use has been increasing tremendously in breast reconstruction and produces satisfying outcomes. However, the lack of standard guidelines for routine screening protocols in breast cancer patients before and after AFG warrants consideration of the safety of AFG use in post-mastectomy and post-lumpectomy reconstruction. This manuscript examines AFG in breast reconstruction publications and details the complications, the mechanism of AFG, as well as the relationship between adipose stem cells (ASCs) and cancer recurrence. The ASCs transferred in AFG act as multiple potent stem cells, which can impact cancer recurrence in various ways. Both in vitro and in vivo studies show that ASCs can stimulate the recurrence of breast cancer. Based on a review of existing evidence, we provide recommendations and guidelines for AFG use in breast reconstruction to aid in clinical decision-making. Further investigations are needed to evaluate the long-term clinical safety of AFG as well as the proposed guidelines.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Understanding why aspirin prevents cancer and why consuming very hot beverages and foods increases esophageal cancer risk. Controlling the division rates of stem cells is an important strategy to prevent cancer

Cancer is, in essence, a stem cell disease. The main biological cause of cancer is that stem cells acquire DNA alterations during cell division. The more stem cell divisions a tissue accumulates over a lifetime, the higher is the risk of cancer in that tissue. This explains why cancer is diagnosed millions of times more often in some tissues than in others, and why cancer incidence increases so dramatically with age. It may also explain why taking a daily low-dose aspirin for several years reduces the risk of developing and dying from cancer. Since aspirin use reduces PGE2 levels and PGE2 fuels stem cell proliferation, aspirin may prevent cancer by restricting the division rates of stem cells. The stem cell division model of cancer may also explain why regular consumption of very hot foods and beverages increases the risk of developing esophageal cancer. Given that tissue injury activates stem cell division for repair, the thermal injury associated with this dietary habit will increase esophageal cancer risk by inducing the accumulation of stem cell divisions in the esophagus. Using these two examples, here I propose that controlling the division rates of stem cells is an essential approach to preventing cancer.

The migration ability of stem cells can explain the existence of cancer of unknown primary site. Rethinking metastasis

Cancers of unknown primary site are metastatic cancers for which primary tumors are not found after detailed investigations. In many cases, the site of origin is not identified even on postmortem examination. These cancers are the fourth most common cause of cancer death. The biological events involved in the development of this type of cancers remain unknown. This manuscript discusses that, like metastatic cells, stem cells have a natural ability to migrate. A cancer of unknown primary site would form when deregulated, premalignant or cancerous stem cells migrated away from their natural tissue and gave rise to a cancer in a new site before or without generating a tumor in their original tissue. It is important to realize that forming a tumor in a tissue is not a prerequisite for stem cells to migrate away from that tissue. This view is in accordance with recent observations that strongly support the tumorigenesis model in which cancer arises from normal stem cells. Evidence has accumulated that cancer stem cells may play a key role in cancer progression and resistance to therapy. Successful treatment of cancer, including that of unknown primary site, may therefore require the development of therapies against cancer stem cells.

The hierarchical model of stem cell genesis explains the man mouse paradox, Peto's paradox, the red cell paradox and Wright's enigma

The central dogma of carcinogenesis is that deleterious mutations accumulate in regularly cycling stem cells and eventually one of the cells will acquire a specific set of mutations which leads to uncontrolled cell proliferation. Each mutation is rare and the specific set is extremely rare so that even though there are millions of stem cells in a small area of mucosa the specific set of mutations to initiate the process of malignancy will only arise in one stem cell at most; hence neoplasia is clonal. But this model predicts that men, who are 1000 times larger than mice and live 30 times as long, should have a vastly increased risk of cancer compared with mice, but they don't (man-mouse paradox). The model also predicts that the prevalence of cancer in men should rise as power function of age and mutagen dose, the former is correct but not the latter (Peto's paradox). Furthermore there are more mitotic divisions in red cell precursors than in all other stem cells combined and yet erythroleukaemia is rare (red cell paradox). The central dogma is also challenged by Wright's enigma; the observation that some gastro-intestinal neoplasms are polyclonal in origin. The problem with the central dogma is the concept of a regularly cycling stem cell. In fact it is possible to produce all the cells that arise in a human lifetime with fewer than 60 rounds of DNA replication separating the zygote from mature differentiated cells in extreme old age. This hierarchical model of stem cell genesis leads to a very low prevalence of cancer, unless the orderly progression of the hierarchy is disturbed by inflammation, ulceration or trauma. This model explains the paradoxes and Wright's enigma. It is suggested that the number of cell divisions that separate the zygote from stem cells is a key variable in carcinogenesis.

Sexual partners, sexually transmitted infections, and prostate cancer risk

BACKGROUND

The etiology of prostate cancer (PCa) is poorly understood. Sexual activity and sexually transmitted infections (STIs) are among factors under scrutiny, with controversial findings to date.

METHODS

We examined the association between the number and gender of sexual partners, STIs and PCa risk in the context of PROtEuS, a population-based case-control study set amongst the mainly French-speaking population in Montreal, Canada. The study included 1590 histologically-confirmed PCa cases diagnosed in a Montreal French hospital between 2005 and 2009, and 1618 population controls ascertained from the French electoral list, Montreal residents, frequency-matched to cases by age. In-person interviews elicited information on sociodemographic, lifestyle and environmental factors. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) between sexually related factors and PCa risk, adjusting for age, ancestry, family history of PCa, and PCa screening history.

RESULTS

Subjects with more than 20 sexual partners in their lifetime had a decreased risk of PCa (OR 0.78, 95% CI 0.61-1.00) as did subjects who specifically had more than 20 female sexual partners (OR 0.72, 95% CI 0.56-0.94). By contrast, having had several male sexual partners appeared to confer some excess in risk of PCa. No association emerged for history of STIs and PCa but STIs prevalence was low.

CONCLUSION

Our findings are in support of a role for the number of sexual partners in PCa development. The gender of sexual partners should be taken into account in future studies investigating this association.

Blunt Breast Trauma: Is There a Standard of Care?

The incidence of female blunt breast trauma (FBBT) is unknown, and there are no established treatment guidelines. The purpose of this study was to establish the incidence of FBBT, define associated injuries, and develop a treatment algorithm. This is a retrospective analysis of FBBT at a Level I trauma center from October 2000 through December 2008. The incidence, mechanism, and severity of injury, associated injuries, therapeutic interventions, and clinical outcomes were evaluated. A total of 14,499 patients were evaluated. Of these, 13,637 were blunt trauma victims and 5,305 were female blunt trauma victims. One hundred and eight (2%) were diagnosed with FBBT. Although the average injury severity score (ISS) was 12.3 for all FBBT patients, 60 per cent of patients had an ISS > 15. Ninety-four per cent were caused by motor vehicle crashes, with the most common injuries being long bone fractures (45%) and rib fractures (44%). One hundred and one (93.5%) of the injuries were simple hematomas managed expectantly; seven patients (6.5%) had expanding hematomas with radiological evidence of active bleeding that ultimately required invasive procedures, with six of them undergoing arteriogram and four successfully embolized. One patient was taken directly to the operating room for surgical ligation of a bleeding vessel. These data represent the largest series of breast injuries ever reported. Because FBBT is a marker for severe associated injuries, our treatment algorithm recommends that women with radiological evidence of active bleeding who are hemodynamically stable be evaluated with a chest arteriogram plus or minus embolization. However, unstable patients with no other source of hemorrhage should undergo definitive urgent operative repair. All other patients should be managed expectantly.

Abuse victimization and risk of breast cancer in the Black Women's Health Study [corrected]

Few studies have examined the relation between abuse victimization and breast cancer, and results have been inconclusive. Using data from 35,728 participants in the Black Women's Health Study, we conducted multivariable Cox regression to estimate incidence rate ratios (IRRs) and 95% confidence intervals (CI) for the association of abuse across the life span (childhood, adolescence, and adulthood) with breast cancer. Incident breast cancer diagnoses were reported during 1995-2009, and abuse histories were reported in 2005. No associations were found between abuse victimization in either childhood or adolescence and breast cancer. We found a weak positive association between abuse in adulthood and breast cancer (IRR = 1.18, 95% CI = 1.03-1.34). IRRs for physical abuse only, sexual abuse only, and both physical and sexual abuse in adulthood, relative to no abuse, were 1.28 (95% CI = 1.09-1.49), 0.96 (95% CI = 0.76-1.20), and 1.22 (95% CI = 1.00-1.49), respectively. IRRs for low, intermediate, and high frequencies of physical abuse in adulthood, relative to no abuse, were 1.28 (95% CI = 1.07-1.52), 1.37 (95% CI = 1.04-1.79), and 1.24 (95% CI = 0.95-1.62), respectively. Our data suggest an increased risk of breast cancer among African-American women who reported physical abuse in adulthood, but there was little evidence of a dose-response relation. These results require confirmation in other studies.

Electrical injury and amyotrophic lateral sclerosis: a systematic review of the literature

Electrical injury may act as a potential precipitating or risk factor for amyotrophic lateral sclerosis (ALS). A systematic review of the literature was undertaken to assess the relationship between electrical injury and the development of ALS. Information for the review was obtained using five medical databases, and from manual searching of individual papers. Patients presenting with a neurological syndrome after electrical injury, including lightning, were included and classified into four categories: ALS; progressive upper motor neurone (UMN) syndrome; progressive lower motor neurone (LMN) syndrome; and non-progressive syndrome. Linear regression and chi2 testing were used for analysis of the data. 96 individuals, comprising 44 with ALS, 1 with a progressive UMN syndrome, 7 with a progressive LMN syndrome and 44 with a non-progressive syndrome, were identified from 31 papers with publication dates between 1906 and 2002. The median interval between electrical injury and disease onset was 2.25 years for all progressive syndromes and just over 1 week for the non-progressive syndrome. The more severe the shock (excluding lightning), the more likely individuals were to have a non-progressive motor syndrome. A non-progressive spinal cord syndrome is associated with more severe electrical injury. Overall, the evidence reviewed does not support a causal relationship between ALS and electric shock.