BREAST CAN­CER CAUSES WE CAN CON­TROL

The dis­ease is a killer, but as many as half of all cases in Canada are linked to causes we can con­trol

Reader's Digest (Canada) - - Front Page - BY LISA BEN­DALL

BREAST CAN­CER IS THE MOST com­mon can­cer among Cana­dian women. Even though the five-year sur­vival rate—87 per cent—has vastly im­proved over the past three decades, one in eight women can still ex­pect to be di­ag­nosed with breast can­cer. (It’s about 100 times rarer in men.) Many risk fac­tors are out of our con­trol: we’re more likely to de­velop the dis­ease the older we get, for in­stance, or the taller we are, although this link may have to do with fac­tors such as child­hood diet that con­trib­ute to height in adult­hood. But cur­rent re­search is find­ing that we can, to some ex­tent, shape our own odds.

“It’s in­cred­i­bly im­por­tant that peo­ple know they are not pow­er­less,” says Su­san­nah Brown, se­nior sci­en­tist at the World Can­cer Re­search Fund (WCRF) in Lon­don, U.K. “There are steps they can take to help re­duce their risk.” Ear­lier this year, WCRF part­nered with the Amer­i­can Institute for Can­cer Re­search to an­a­lyze more than 100 stud­ies draw­ing on data from mil­lions of women around the world. They found strong ev­i­dence of low­ered breast can­cer risk with sim­ple life­style in­ter­ven­tions. “It’s never too late to get health­ier,” says Brown. “But the ear­lier you start, the bet­ter.”

Here’s how to lower your risk.

1. RE­DUCE YOUR AL­CO­HOL IN­TAKE

If you’re drink­ing for your health, think again. What you’re do­ing is rais­ing your risk of seven can­cers, in­clud­ing liver can­cer. One drink a day in­creases your chances of de­vel­op­ing breast can­cer specif­i­cally by as much as 10 per cent. Two drinks and you dou­ble it by up to 20 per cent.

“A lot of women are shocked by that,” says Dr. Ju­lian Kim, a ra­di­a­tion on­col­o­gist with Can­cer Care Man­i­toba in Win­nipeg. “They drink a glass of wine to re­lax, and they think they’re get­ting away scot-free.” Al­co­hol can in­crease lev­els of es­tro­gen, which, like other hor­mones, de­liv­ers mes­sages that con­trol cell di­vi­sion in the body. In­creased life­time es­tro­gen ex­po­sure is as­so­ci­ated with breast can­cer. That’s why get­ting your first pe­riod be­fore age 12 and reach­ing menopause af­ter 55 are risk fac­tors.

Plus, when we me­tab­o­lize al­co­hol, it’s con­verted into ac­etalde­hyde, a toxic by-prod­uct that can dam­age DNA and in­ter­fere with our abil­ity to re­pair it. “There is no safe amount women can drink with­out in­creas­ing their risk of breast can­cer,” says Brown. “How­ever, the women who drink the most al­co­hol are at the great­est risk.”

When it comes to an­other com­mon vice, smok­ing, the news is sur­pris­ing. Although smok­ing-re­lated ill­nesses cause about 100 deaths a day in Canada and may be im­pli­cated in some breast can­cers, “smok­ing is not as strong a risk fac­tor for breast can­cer as it is for other can­cers,” notes Shawn Chirrey, se­nior man­ager of health pro­mo­tion for the Cana­dian Can­cer So­ci­ety in Toronto.

2. BE PHYS­I­CALLY AC­TIVE

Ex­er­cise low­ers the risk of breast can­cer, and be­ing in­ac­tive in­creases it. The pro­tec­tive ef­fects vary de­pend­ing on whether or not you’re post­menopausal, whether the ex­er­cise is mod­er­ate or vig­or­ous, and how much time you de­vote to phys­i­cal ac­tiv­ity.

“There’s a dose re­sponse. The more ex­er­cise you do, the greater the ben­e­fit,” says Dr. Christine Frieden­re­ich, a Calgary-based can­cer epi­demi­ol­o­gist at Al­berta Health Ser­vices. In all, about 17 per cent of breast can­cer can be blamed on in­ac­tiv­ity. Aim for at least 30 min­utes of brisk ex­er­cise a day for pre­ven­tion, but re­mem­ber that any ac­tiv­ity is bet­ter than none. “We know it also re­duces the risk of at least 13 other can­cers,” says Frieden­re­ich, who is part of a project to quan­tify all mod­i­fi­able risk fac­tors for all can­cers across the coun­try.

It’s likely there are many ways phys­i­cal ac­tiv­ity is pro­tec­tive against breast can­cer. Ex­er­cise de­creases lev­els of es­tro­gen in post­menopausal women and im­proves the im­mune sys­tem, and if you’re ac­tive out­doors, vi­ta­min D ex­po­sure from the sun may even make a dif­fer­ence. How­ever, fur­ther re­search is needed to un­der­stand the im­pact of dif­fer­ent kinds of ac­tiv­ity.

It can be chal­leng­ing to in­cor­po­rate ex­er­cise into our hec­tic lives, but Chirrey says that pol­icy shifts in work­places and municipalities are help­ful. Em­ploy­ers can pro­vide dis­count gym mem­ber­ships or find ways to in­crease ac­tiv­ity lev­els, and cities can build bike lanes. “En­vi­ron­ments can en­cour­age peo­ple to make phys­i­cal ac­tiv­ity part of their day,” he says.

3. CON­TROL YOUR WEIGHT

Be­ing over­weight or obese through­out adult­hood is a risk fac­tor for post­menopausal breast can­cer (a cat­e­gory that in­cludes most cases; an es­ti­mated 83 per cent of breast can­cers are di­ag­nosed af­ter the age of 50). Put­ting on pounds af­ter menopause also makes you more likely to get breast can­cer. “Ev­ery 10 kilo­grams of post­menopausal weight gain is as­so­ci­ated with an 18 per cent rel­a­tive in­creased risk,” notes Kim. (“Rel­a­tive risk” means you’re 18 per cent more likely to get breast can­cer than some­one of sim­i­lar age and body type who hasn’t gained weight.) Main­tain­ing a healthy weight pro­tects against other types of can­cer as well, not to men­tion di­a­betes, heart dis­ease and stroke.

As with ex­er­cise, there’s no sin­gle rea­son why weight in­flu­ences breast can­cer risk. What makes it even more com­plex is that car­ry­ing ex­tra weight as a young woman (ages 18 to 30) ap­pears to be pro­tec­tive—per­haps be­cause heav­ier women fre­quently have dis­rupted hor­monal cy­cles and re­duced es­tro­gen lev­els.

Af­ter menopause, how­ever, fat tis­sue is a main source of es­tro­gen. Re­searchers have also iden­ti­fied links be­tween obe­sity and chronic in­flam­ma­tion of fat tis­sue, which may be re­spon­si­ble for an el­e­vated can­cer risk in the breast. The same ap­plies to higher lev­els of in­sulin. What­ever the rea­son, con­trol­ling weight, par­tic­u­larly af­ter menopause, will pro­tect you against breast can­cer.

4. AVOID HOR­MONE RE­PLACE­MENT THER­APY

Hor­mone re­place­ment ther­apy (HRT) is used to treat symp­toms of menopause caused by sharply de­clin­ing es­tro­gen lev­els, such as hot flashes, sleep dis­rup­tion and vagi­nal dry­ness. It in­volves tak­ing sup­ple­men­tal es­tro­gen by pill or patch, some­times in com­bi­na­tion with the hor­mone pro­gestin. But ex­perts es­ti­mate that HRT, which ex­poses post­menopausal women to in­creased es­tro­gen, causes 15 per cent of new cases of breast can­cer. “HRT is to be avoided if at all pos­si­ble, ex­cept for ex­treme cases when women are re­ally suf­fer­ing with menopause,” says Frieden­re­ich.

“It’s im­por­tant to have a con­ver­sa­tion with your health care provider,” adds Chirrey. “Talk about the risks and ben­e­fits of HRT.” De­pend­ing on your symp­toms, a physi­cian may sug­gest lo­cal es­tro­gen ther­apy, which uses low-dose vagi­nal es­tro­gen, re­leased by a cream or ring, and car­ries a much lower risk be­cause very lit­tle es­tro­gen will get into your blood­stream. If you do opt for hor­mone re­place­ment ther­apy, use it for as short a pe­riod as pos­si­ble, and no more than five years. The el­e­vated risk of breast can­cer dis­si­pates a few years af­ter stop­ping HRT.

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