Expert: Claes-Gustaf Nordquist, M.D. - 12/28/2008

Question
Hi you answered my question a few months ago, but now there is another factor or question. If I had DCIS that was 50% progesterone fed should I ever take progesterone again? I went for fertility treatment. I took FSH and HCG, which do not increase my risk and have been inseminated recently.
 They want me to take 200 mg (100 mg 2x/day) of vaginal progesterone for up to 12 wks, to maintain the pregnancy. Is this stupid?  No one will admit that progesterone causes breast cancer.  Not the nurses, my gp, and fertility doctors.  They say nothing is proven and people still prescribe it.  I took 400 mg of oral progesterone and after 14 yrs had 50% progesterone fed DCIS.  I went through hell.  I can't do that again.  There is no side effect of BC on the vaginal prog info.  Should I take it?  It's their protocol.  They said because of the fertility meds I took, it's necessary.  I'm scared.  But I could and would like to be wrong.  No one admits it's what caused the DCIS.  It seems so obvious to me.  Why don't the experts agree?  I'd like to be wrong.  Can I take a low dose vaginally inserted progesterone for a short time without worry of a recurrence?
I've wanted children my whole life.  I do really need my breasts and life.

See previous question below. { xpert: Claes-Gustaf Nordquist, M.D. - 10/27/2008

Question
Iwould like to know the following:How much does a full term pregnancy increase a womans cancer risk if they had DCIS.  I was treated and cured of DCIS in my left breast 4 yrs ago. It was 50 % progesterone fed, I think due to taking 300-400 mgs of progesterone daily for 13 yrs for PMS.  
I would like to have a child.  
History is left breast DCIS, 3 surgeries, because it was too small to see to get clean margins the first time, and 6 wks radiation, which I sailed through.  I am healthy, in my 40s and running out of time.  What are the risks with me having a baby? }

Answer
I understand your concern BUT development of any cancer is a long and complex process. Yes in the development of breast cancers hormones do play a role. But they are not the only factors involved. In a case of a cancer in situ (stage 0) of the breast, the kind of cancer you were treated for, it has in your case been removed and since it was a stage 0 tumor you are now cured of it. So any fear of breast cancer in your case can ONLY - if rational - be associated with the risk of a new tumor. If that would happen to you it is an open question to what extent that possible tumor would be hormone dependent. Besides since I wrote that tumor forming is a long process (years) a treatment process of up to only 12 weeks (= 3 months) most probably would be without any such effect even if you previously have been on progesterone for a long time. Compare it to a smoker (90% of all lung cancers are due to smoking). Say that a smoker has smoked for 13 years and then stopped smoking. How much extra risk would a relapse of 12 weeks of smoking give that smoker? VERY LITTLE - if any! And smoking is MUCH MORE associated with lung cancer than progesterone with breast cancer! So go ahead! Good luck! Happy new year!