After treat­ment of breast can­cer to the sat­is­fac­tion of her oncol­o­gist, should a woman who desire to get preg­nant be dis­cour­aged from doing so? A very crit­i­cal ques­tion con­sid­er­ing the fact that there are close to half a mil­lion breast can­cer sur­vivors liv­ing in the US and are in the child­bear­ing age.

For a very long time, coun­sel­ing of women regard­ing preg­nancy was depen­dent on the fact that estro­gen increases dur­ing preg­nancy and because estro­gen has some effects on both estro­gen recep­tor pos­i­tive and estro­gen recep­tor neg­a­tive breast can­cers, its prob­a­bly bet­ter if women avoid pregnancy-unless of course another woman is car­ry­ing for them, a ges­ta­tional car­rier. This rec­om­men­da­tion is not based on strong sci­en­tific evidence.

Safety of preg­nancy after breast can­cer treat­ment. All the pub­lished reports included a total of 1417 women who got preg­nant after breast can­cer treat­ment and 18059 who sur­vived breast can­cer and did not get preg­nant. Women who got preg­nant fol­low­ing breast can­cer diag­no­sis had sig­nif­i­cantly bet­ter sur­vival com­pared to women who did not get preg­nant. In fact, those who got preg­nant were more than 40% less likely to die because of breast cancer.

Impor­tant caveat to these stud­ies is the healthy mother bias-the ten­dency of health­ier women to desire and attempt preg­nancy and the less healthy women to avoid preg­nancy. This may inflate the safety of becom­ing preg­nant after breast can­cer treat­ment. Stud­ies also largely did not address the chance for recur­rence. Nev­er­the­less, no study showed detri­men­tal effect in breast can­cer sur­vivors who become preg­nant. The largest of these stud­ies pub­lished by The Dan­ish Breast Can­cer Coop­er­a­tive Group was a pop­u­la­tion based study and included over 10,000 women who sur­vived breast can­cer and were under the age of 45. Three hun­dreds and sixty-seventy one women expe­ri­enced 465 preg­nan­cies and 236 deliv­er­ies. Women who got pregnant-full term or spon­ta­neous mis­car­riage, were at least 30% less likely to die from breast can­cer. Women with low risk breast can­cers enjoyed 45% higher chance for sur­vival after full term preg­nancy than sim­i­lar women who did not get pregnant.

How long should women wait after breast can­cer treat­ment before attempt­ing preg­nancy? The major­ity of experts rec­om­mend wait­ing for about two years as the major­ity of recur­rences takes place within this period. There are dif­fer­ences in recur­rence pat­tern, how­ever, between estro­gen recep­tor neg­a­tive and estro­gen recep­tor pos­i­tive tumors. Estro­gen recep­tor neg­a­tive tumors are more com­mon in younger women and tend to recur earlier-within 2years after treat­ment. Recur­rence of estro­gen recep­tor pos­i­tive can­cers remain as high as 4–5% per year for about 15 years.

Preg­nancy in BRCA1 and BRCA2 muta­tion car­ri­ers. In BRCA1 preg­nancy does not seem to increase the risk of early onset breast can­cer. In BRCA2 car­ri­ers, preg­nancy may cause a bor­der­line increase in risk of breast can­cer before 50, espe­cially when first preg­nancy after age 40.

Breast feed­ing is rec­om­mended when­ever pos­si­ble in women treated for breast can­cer, even if they are BRCA car­ri­ers and does not appear to impact breast can­cer prog­no­sis and may even be pro­tec­tive in some cases.

Con­tra­cep­tion. If preg­nancy is not desired as dur­ing breast can­cer treat­ment and the fol­low up period after treat­ment non hor­monal con­tra­cep­tion is rec­om­mended such as IUD or bar­rier method e.g. con­dom. BRCA1 car­ri­ers may show an increased risk for early onset breast can­cer if they use oral con­tra­cep­tive pills before the age of 30 or for more than 5 years.

Young women diag­nosed with breast can­cer are com­monly very con­cerned about their future fer­til­ity and safety of preg­nancy after treat­ment. Proper coun­sel­ing enables them to make appro­pri­ate deci­sions about future repro­duc­tion and fer­til­ity preser­va­tion. At the end of the day, most of the breast can­cer bat­tles will be won, some will be lost, preg­nancy does not appear to con­tribute to that loss.