THE GREAT DE­BATES

Expat Living (Singapore) - - Health & Fitness - Dr Geor­gette Chan #11-09 Mount El­iz­a­beth Med­i­cal Cen­tre, 3 Mount El­iz­a­beth 6836 5167 | geor­get­techan.com.sg

Breast can­cer screen­ing has been a source of con­tro­versy for decades, with some med­i­cal ex­perts and pa­tients ques­tion­ing whether the ben­e­fits of mammography out­weigh the risks. Cur­rently, most women use mammography as their main form of rou­tine screen­ing, while other meth­ods like mag­netic res­o­nance imag­ing ( MRI) are typ­i­cally con­ducted only for fur­ther eval­u­a­tion, or in con­junc­tion with mammography, par­tic­u­larly for those women at high risk. Though most ma­jor health or­gan­i­sa­tions have con­cluded that mammography is a valu­able screen­ing tool, oth­ers main­tain that MRI is more ef­fec­tive and should be pri­mar­ily con­ducted even for those women with an av­er­age risk of de­vel­op­ing breast can­cer.

What’s more, there’s also con­tro­versy over the age at which women should start screen­ing for breast can­cer – the main rea­son be­ing that younger women have denser breasts, which makes it dif­fi­cult to in­ter­pret mam­mo­grams in women be­low 50, or be­low menopausal age. After menopause, the breast’s glan­du­lar tis­sue is re­placed by fatty tis­sue, mak­ing mam­mo­graphic in­ter­pre­ta­tions more ac­cu­rate. As a re­sult, mammography isn’t gen­er­ally con­sid­ered an ef­fec­tive tech­nique for younger women.

The age is­sue aside, women with denser breasts are usu­ally en­cour­aged to un­dergo MRI or ul­tra­sound screen­ings, as mam­mo­grams don’t al­ways pick up can­cers hid­den by the dense tis­sue, pro­duc­ing false neg­a­tives – when find­ings ap­pear nor­mal even though breast can­cer is present, creat­ing a false sense of se­cu­rity and a pos­si­ble de­lay in can­cer di­ag­no­sis. So, while it’s true that MRI has been shown to rule out the pres­ence of can­cer to a high de­gree of cer­tainty, mak­ing it an ex­cel­lent tool for screen­ing – par­tic­u­larly for pa­tients at high ge­netic risk or those with dense tis­sue – many ex­perts point out that MRI can miss some can­cers that would oth­er­wise be de­tected by mammography.

And, while MRI is con­sid­ered to be more sen­si­tive, mammography is con­sid­ered to be more spe­cific. Breast sur­geon DR GEOR­GETTE CHAN, for in­stance, rec­om­mends MRI scans only in com­bi­na­tion with mam­mo­grams for cer­tain groups of pa­tients, in­clud­ing young women with dense breasts, those with a strong fam­ily his­tory of breast can­cer and those with breast im­plants. Mammography, she says, has an ac­cu­racy rate as high as 90 to 95 per­cent, and has proven ef­fec­tive in de­tect­ing can­cers early; early dis­cov­ery is associated with a 20 per­cent drop in breast can­cer mor­tal­ity.

Ac­cord­ing to Dr Chan, re­cent ad­vances in the field of mammography make the screen­ing process even more ef­fec­tive. One ex­am­ple is 3D mammography (to­mosyn­the­sis), which is an ex­ten­sion of a dig­i­tal mam­mo­gram. “The breast is com­pressed once and the ma­chine takes many low-dose x-rays as it moves over the breast,” she ex­plains. “Then, the im­ages are com­bined to give a three-di­men­sional pic­ture. This method uses more ra­di­a­tion than the stan­dard two-view mam­mo­gram, but it may see prob­lem ar­eas more clearly and may pos­si­bly find more can­cers.”

Ra­di­a­tion is, of course, a key fac­tor in the can­cer screen­ing de­bate. Like nor­mal x-rays, mammography uses ion­is­ing ra­di­a­tion to cre­ate im­ages that are then an­a­lysed for any ab­nor­mal­i­ties. Ac­cord­ing to USbased can­cer or­gan­i­sa­tion Su­san G. Komen, while the ra­di­a­tion ex­po­sure dur­ing mammography can in­crease the risk of breast can­cer over time, this in­crease in risk is very small, with stud­ies show­ing that the ben­e­fits of mammography over­shadow the pos­si­ble dan­gers from ra­di­a­tion ex­po­sure, par­tic­u­larly for women 50 and older. Dr Chan agrees, say­ing, “The amount of ra­di­a­tion is very low dose, akin to that of a cou­ple of chest x-rays and much lower than a PET scan or a CT scan. So, the risk of harm is low, es­pe­cially if done only yearly (from 40 to 50), and then ev­ery two years (from 50 on­wards), as we rec­om­mend.” Nev­er­the­less, the con­cern over ex­po­sure to small doses re­mains, and it’s up to the in­di­vid­ual to make that choice for her­self.

There’s also the is­sue of false pos­i­tives – when find­ings in­di­cate can­cer when no can­cer is ac­tu­ally present. Some med­i­cal ex­perts and pa­tients feel that, when tak­ing into ac­count the fre­quency of false pos­i­tives in mammography and the po­ten­tial for caus­ing un­nec­es­sary dis­tress, the risks of mammography off­set the ben­e­fits. This is be­cause many women who re­ceive false pos­i­tive results be­come anx­ious and fear­ful about the pos­si­bil­ity of hav­ing breast can­cer, and must re­turn for anx­i­ety- in­duc­ing fol­low- ups and test­ing, and un­nec­es­sary biop­sies. On the other hand, it can be ar­gued that this po­ten­tial dis­tress may be out­weighed by the pos­si­bil­ity of de­tect­ing can­cer in its early stages.

MRIS can present false pos­i­tives, too. In fact, Dr Chan says that MRI scans cre­ate more false pos­i­tive results than mam­mo­grams do, be­cause the scans are more de­tailed. “There’s a lot of over­lap be­tween nor­mal and ab­nor­mal tis­sue. Even the tim­ing of the scan in re­la­tion to the men­strual cy­cle can make a dif­fer­ence be­cause of the hor­monal in­flu­ence.”

Com­fort is another con­sid­er­a­tion that’s cen­tral to women’s screen­ing de­ci­sions. Many women forgo an MRI based on the claus­tro­pho­bic sen­sa­tion, and the length of time the pro­ce­dure takes. Ac­cord­ing to Dr Chan, while MRI scans are not painful since breasts are not com­pressed, the dis­com­fort comes with hav­ing to lie on one’s belly for 45 min­utes in a con­fined space. She also notes that MRI re­quires an in­tra­venous in­jec­tion of a dye via IV for bet­ter vi­su­al­i­sa­tion, mak­ing it more of an in­va­sive pro­ce­dure. On the other hand, some feel that MRI is less un­com­fort­able than mammography – it re­ally de­pends on the in­di­vid­ual’s com­fort level.

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