Changes

==Risk factors==  

==Risk factors==  

Many factors affect the incidence of breast cancer in any given population of women including:

Many factors may potentially affect the incidence of breast cancer in any given population of women including:

*'''Age''': this is a complex relationship, with the steepest rise in diagnosis occurring between the ages of 40 and 60, however pre- and post-menopausal breast cancers tend to behave differently. Increasing age increases the risk that at some point in her life a woman will contract breast cancer, rising from 1 in 231 (0.5% risk) aged under 40 to 1 in 7 at age 90. <ref> http://www.breastcancer.org/cmn_who_indrisk.html </ref>.<ref> http://www.breastcancer.org/cmn_who_indrisk.html </ref>

*'''Age''': this is a complex relationship, with the steepest rise in diagnosis occurring between the ages of 40 and 60, however pre- and post-menopausal breast cancers tend to behave differently. Increasing age increases the risk that at some point in her life a woman will contract breast cancer, rising from 1 in 231 (0.5% risk) aged under 40 to 1 in 7 at age 90. <ref> http://www.breastcancer.org/cmn_who_indrisk.html </ref>.<ref> http://www.breastcancer.org/cmn_who_indrisk.html </ref>

*'''Obesity''': this is a more significant risk factor in postmenopausal women.  Before menopause, the effect is unclear. <ref> http://society.guardian.co.uk/cancer/story/0,,686105,00.html </ref>

*'''Obesity''': this is a more significant risk factor in postmenopausal women.  Before menopause, the effect is unclear. <ref> http://society.guardian.co.uk/cancer/story/0,,686105,00.html </ref>

*'''Family history''' if such a history involves having several generations affected by breast cancer or having many relatives diagnosed with breast cancer at less than 50 years old <ref> http://www.breastcancer.org/cmn_who_indrisk.html </ref>

*'''Family history''' if such a history involves having several generations affected by breast cancer or having many relatives diagnosed with breast cancer at less than 50 years old <ref> http://www.breastcancer.org/cmn_who_indrisk.html </ref>

*'''Abortion''' <ref>[[abortion]]</ref>

*'''Abortion''': There is some controversy as to whether abortion increases the risk of breast cancer. <ref>http://www.cancercouncil.com.au/editorial.asp?pageid=245</ref>

*'''Prolonged uninterrupted exposure to estrogen''' (e.g. by having an early [[menarche]] and late [[menopause]] or by having no full-term pregnancies).<ref> http://www.breastcancer.org/cmn_who_indrisk.html </ref>

*'''Prolonged uninterrupted exposure to estrogen''' (e.g. by having an early [[menarche]] and late [[menopause]] or by having no full-term pregnancies).<ref> http://www.breastcancer.org/cmn_who_indrisk.html </ref>

*'''Personal history of breast cancer'''

*'''Personal history of breast cancer'''