Breast cancer risk factors


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Risk factors for breast cancer, modifiable, genetics, environmental, relative occurrence, women at risk, false perception.

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Breast cancer risk factors

  1. 1. Risk factors for Breast Cancer The role of genetics Professor Tarek Tawfik Amin Public Health Cairo University
  2. 2. Introduction o A risk factor isanything that affectsthechance of getting adisease, such ascancer. o About 70% of women diagnosed with BC did not haveknown risk factors. o It ishard to definethecontribution of different risk factorsin thedevelopment of BC. o Multiplicity of risk factorsincreasethe likelihood for diseasedevelopment.
  3. 3. Breast cancerrisk factors Menses menopause Dense breast tissue Aging Personal Breast cancer Benign breast Lesions Family history Genetics Gender Breast cancer Physical Inactivity Obesity Alcohol Radiotherapy HR Therapy Oral contraception Breast feeding Having children Breast Cancer Non-modifiable ModifiableControversial /uncertain Personal behavioral, environmental Anti prespirants Anti prespirants BrasBras Induced abortion Induced abortion Breast implants Breast implants TobaccoTobacco Night work Night work Diet vitamins Diet vitamins Enviro. chemicals Enviro. chemicals
  4. 4. Non-modifiable risk factors Gender o Simply being awoman isthemain risk factor for developing breast cancer (BC). o BC isabout 100 timesmorecommon among women than men. o Breast cellsareconstantly exposed to the growth-promoting effectsof thefemale hormonesestrogen and progesterone.
  5. 5. Non-modifiable risk factors Aging o Therisk of developing breast cancer increases with age. o About 1 out of 8 invasivebreast cancersare found in women < 45. o About 2 of 3 invasivebreast cancersarefound in women age55 or older.
  6. 6. Non-modifiable risk factors Genetic risk factors o About 5% to 10% of breast cancer casesare thought to behereditary, resulting directly from genedefects(called mutatio ns) inherited from aparent.
  7. 7. Genes in breast cancer BRCA1 and BRCA2 mutations:  o Themost common causeof hereditary breast cancer. o In normal cells, thesegeneshelp prevent cancer by making proteinsthat keep thecellsfrom growing abnormally. o Inheritanceof amutated genesincreasetherisk for BC. o Therisk may beashigh as80% for membersof some familieswith BRCA mutations. Cancerstend to occur in younger women and moreoften affect both breasts, with increased risk for developing other cancers(ovarian). o BRCA mutationsarefound most often in Jewish women of Ashkenazi (Eastern Europe) origin, but they can occur in any racial or ethnic group.
  8. 8. Genes • BRCA1: A geneon chromosome17 that normally helpsto suppresscell growth. A person who inherits certain mutations(changes) in aBRCA1 genehasa higher risk of getting breast, ovarian, prostate, and other typesof cancer. • BRCA2: A geneon chromosome13 that normally helpsto suppresscell growth. A person who inherits certain mutations(changes) in aBRCA2 genehasa higher risk of getting breast, ovarian, prostate, and other typesof cancer.
  9. 9. Genes in breast cancer
  10. 10. Changes in othergenes:   Thesegenemutationsaremuch rarer and often do not increasetherisk of breast cancer asmuch astheBRCA genes.  They arenot frequent causesof inherited breast cancer. ATM: TheATM genenormally helpsrepair damaged DNA. Inheriting 2 abnormal copiesof thisgenecausesthediseaseataxia-telangiectasia. Inheriting onemutated copy of thisgenehasbeen linked to ahigh rateof breast cancer in somefamilies. p53: Inherited mutationsof thep53 tumor suppressor genecausethe Li- Fraumeni syndro me. Peoplewith thissyndromehavean increased risk of developing breast cancer, aswell asseveral other cancerssuch asleukemia, brain tumors, and sarcomas. Genes in breast cancer
  11. 11. Genes in breast cancer
  12. 12. Genes in breast cancer CHEK2: TheLi-Fraumeni syndromecan also becaused by inherited mutationsin theCHEK2 gene. Inheritanceof mutated CHEK2 can increasebreast cancer risk of about twofold. PTEN: ThePTEN genenormally helpsregulatecell growth. Inherited mutationscause Co wden syndro me, arare disorder with increased risk for both benign and malignant breast tumors, tumorsof thedigestivetract, thyroid, uterus, and ovaries.
  13. 13. Genes in breast cancer CDH1: Inherited mutationsin thisgenecause hereditary diffuse gastric cancer. Women with mutationsin thisgenealso havean increased risk of invasivelobular breast cancer. STK11: Defectsin thisgenecan lead to Peutz-Jeghers syndro me. Pigmented spotson their lipsand mouths, polypsin theurinary and gastrointestinal tracts, and an increased risk of many typesof cancer, including breast cancer.
  14. 14. Non-modifiable risk factors Family history of breast cancer: o Having onefirst-degreerelative(mother, sister, or daughter) with breast cancer approximately doublesa woman'srisk. o Having 2 first-degreerelativesincreasesher risk about 3-fold. o Women with afamily history of breast cancer in a father or brother havean increased risk of BC. o Over 85% of women with BC do no t haveafamily history of disease.
  15. 15. Personal history of breast cancer: • A woman with cancer in onebreast hasa3- to 4-fold increased risk of developing anew cancer in theother breast or in another part of thesamebreast. Non-modifiable risk factors
  16. 16. Race and ethnicity o Whitewomen areslightly morelikely to develop breast cancer than areAfrican-American women, but African-American women aremorelikely to dieof thiscancer. o However, in women < 45 yearsof age, breast cancer ismorecommon in African- American women. o Asian, Hispanic, and Native-American women havea lower risk of developing and dying from breast cancer. Non-modifiable risk factors
  17. 17. Dense breast tissue o Women with denser breast tissue (mammogram) havemoreglandular tissueand lessfatty tissue, and haveahigher risk of breast cancer. o Unfortunately, densebreast tissuecan also makeit harder to spot problemson mammograms. Non-modifiable risk factors
  18. 18. Certain benign breast conditions • Women diagnosed with certain benign breast conditionsmay havean increased risk of breast cancer. Non-modifiable risk factors
  19. 19. Proliferative lesions without atypia:  Theseconditionsshow excessivegrowth of cellsin theductsor lobulesof thebreast tissue. They seem to raiseawoman'srisk of breast cancer slightly (1½ to 2 timesnormal). They include: • Usual ductal hyperplasia(without atypia) • Complex fibroadenoma • Sclerosing adenosis • Several papillomas(called papillomatosis) • Radial scar Benign breast conditions
  20. 20. Proliferative lesions with atypia:  They haveastronger effect on breast cancer risk, raising it 4 to 5 timeshigher than normal. Thesetypesof lesionsinclude: • Atypical ductal hyperplasia(ADH) • Atypical lobular hyperplasia(ALH) Women with afamily history of breast cancer and either hyperplasiaor atypical hyperplasiahavean even higher risk of developing abreast cancer. Benign breast conditions
  21. 21. Lobularcarcinoma in situ • In lobular carcinomain situ (LCIS) (also called lo bular neo plasia) issometimes grouped with ductal carcinomain situ (DCIS) asanon-invasivebreast cancer, but it differs from DCISin that it doesn’t seem to become an invasivecancer if it isn’t treated. • Women with thiscondition havea7- to 11- fold increased risk of developing invasive cancer in either breast. Benign breast conditions
  22. 22. Menstrual periods o Early menarche(beforeage12) and/or late menopause(after age55) haveaslightly higher risk of breast cancer. o Theincreasein risk may bedueto alonger lifetimeexposureto thehormonesestrogen and progesterone. Non-modifiable risk factors
  23. 23. Previous chest radiation • Radiation therapy to thechest areaastreatment for another cancer (such asHodgkin diseaseor non- Hodgkin lymphoma) haveasignificantly increased risk for breast cancer. • Therisk of developing breast cancer from chest radiation ishighest if theradiation wasgiven during adolescence, when thebreastswerestill developing. • Radiation treatment after age40 doesnot seem to increasebreast cancer risk. Modifiable risk factors
  24. 24. Having children o Women who havehad no children or who had their first child after age30 haveaslightly higher breast cancer risk. o Having many pregnanciesand becoming pregnant at ayoung agereducebreast cancer risk. o Pregnancy reducesawoman'stotal number of lifetimemenstrual cycles, which may bethe reason for thiseffect. Modifiable risk factors
  25. 25. Recent oral contraceptive use o Women using oral contraceptiveshavea slightly greater risk of breast cancer than women who havenever used them. o Women who stopped using oral contraceptives morethan 10 yearsago do not appear to have any increased breast cancer risk. Modifiable risk factors
  26. 26. Hormone therapy aftermenopause • Hormonetherapy with estrogen (often with progesterone) has been used for many yearsto help relievesymptomsof menopauseand to prevent osteoporosis. Thereare2 main typesof hormonetherapy. - For women who still haveauterus, both estrogen and progesterone(known as co mbined ho rmo ne therapy or HT). Progesteroneisneeded becauseestrogen alonecan increasethe risk of cancer of theuterus. - For women with hysterectomy, estrogen alonecan be prescribed. Modifiable risk factors
  27. 27. Combined hormonetherapy o Using combined hormonetherapy after menopauseincreasestherisk of breast cancer. It may also increasethechancesof dying from breast cancer. o Thisincreasein risk can beseen with aslittle as2 yearsof use. Combined HT also increases thelikelihood that thecancer may befound at amoreadvanced stage. o A woman'sbreast cancer risk seemsto return to that of thegeneral population within 5 years of stopping combined treatment.
  28. 28. Modifiable risk factors Breast-feeding • Breast-feeding may slightly lower breast cancer risk, especially if breast-feeding is continued for 1½ to 2 years. • Theexplanation for thispossibleeffect may be that breast-feeding reducesawoman'stotal number of lifetimemenstrual cycles.
  29. 29. Alcohol o Theuseof alcohol isclearly linked to an increased risk of developing breast cancer. o Therisk increaseswith theamount of alcohol consumed. Compared with non-drinkers, women who consume1 alcoholic drink aday haveavery small increasein risk. o Thosewho have2 to 5 drinksdaily haveabout 1½ timestherisk of women who drink no alcohol. Modifiable risk factors
  30. 30. Being overweight orobese o Being overweight or obesehasbeen found to increasebreast cancer risk, especially for women after menopause. o Having morefat tissueafter menopausecan increasethe chanceof getting breast cancer by raising estrogen levels. o Overweight tend to havehigher blood insulin levels. o Higher insulin levelshavealso been linked to somecancers, including breast cancer. o Therisk appearsto beincreased for women who gained weight asan adult but may not beincreased among thosewho havebeen overweight sincechildhood. o Excessfat in thewaist areamay affect risk morethan thesame amount of fat in thehipsand thighs. Modifiable risk factors
  31. 31. Physical inactivity o Evidenceisgrowing that physical activity in theform of exercisereducesbreast cancer risk. o In onestudy from theWomen'sHealth Initiative(WHI) aslittleas1.25 to 2.5 hours per week of brisk walking reduced awoman's risk by 18%. o Walking 10 hoursaweek reduced therisk a littlemore. Modifiable risk factors
  32. 32. Factors with uncertain, controversial, orunproven effect on breast cancerrisk Diet and vitamin intake o Studieshavelooked at theamount of fat in thediet, intakeof fruitsand vegetables, and intakeof meat. No clear link to breast cancer risk wasfound. o No study hasshown that taking vitaminsreduces breast cancer risk. o Most studieshavefound that breast cancer isless common in countrieswherethetypical diet islow in total fat, low in polyunsaturated fat, and low in saturated fat. o It isclear that caloriesdo count, and fat isamajor sourceof these. High-fat dietscan lead to being overweight or obese, which isabreast cancer risk factor.
  33. 33. Antiperspirants o Rumorshavesuggested that chemicalsin underarm antiperspirantsareabsorbed through theskin, interferewith lymph circulation, causetoxinsto build up in thebreast, and eventually lead to breast cancer. o Thereisvery littleevidenceto support thisrumor. o Onesmall study hasfound tracelevelsof parabens(used as preservativesin antiperspirantsand other products), which haveweak estrogen-likeproperties, in asmall sampleof breast cancer tumors. o But thisstudy did not look at whether parabenscaused the tumors. Factors with uncertain, controversial, orunproven effect on breast cancerrisk
  34. 34. Bras o Internet e-mail rumorsand at least onebook havesuggested that brascausebreast cancer by obstructing lymph flow. o Thereisno good scientific or clinical basisfor thisclaim. Factors with uncertain, controversial, orunproven effect on breast cancerrisk
  35. 35. Induced abortion • Several studieshaveprovided very strong data that neither induced abortionsnor spontaneous abortions(miscarriages) havean overall effect on therisk of breast cancer Factors with uncertain, controversial, orunproven effect on breast cancerrisk
  36. 36. Breast implants o Several studieshavefound that breast implants do not increasebreast cancer risk, although siliconebreast implantscan causescar tissueto form in thebreast. o Implantsmakeit harder to seebreast tissueon standard mammograms, but additional x-ray picturescalled implant displacement viewscan beused to examinethebreast tissuemore completely. Factors with uncertain, controversial, orunproven effect on breast cancerrisk
  37. 37. Chemicals in the environment o Of special interest arecompoundsin theenvironment that found to haveestrogen-likeproperties. o Thesecould in theory affect breast cancer risk. For example, substancesfound in someplastics, certain cosmeticsand personal careproducts, pesticides (such asDDE), and PCBs(polychlorinated biphenyls) seem to havesuch properties. o Research doesnot show aclear link between breast cancer risk and exposureto thesesubstances. Factors with uncertain, controversial, orunproven effect on breast cancerrisk
  38. 38. Tobacco smoke o For along time, studiesfound no link between cigarettesmoking and breast cancer. o In recent yearsthough, somestudieshave found that smoking may increasetherisk of breast cancer. Theincreased risk seemsto affect certain groups, such aswomen who started smoking when they wereyoung. Factors with uncertain, controversial, orunproven effect on breast cancerrisk
  39. 39. Night work o Several studieshavesuggested that women who work at night — for example, nurseson a night shift — may havean increased risk of developing breast cancer. o Someresearchersthink theeffect may bedue to changesin levelsof melatonin, ahormone whoseproduction isaffected by thebody's exposureto light, but other hormonesarealso being studied. Factors with uncertain, controversial, orunproven effect on breast cancerrisk
  40. 40. Thank you