Metformin and Breast Cancer

Trial dosage is 1500mg / day.  During the first two weeks you take half that.  GI tract problems are the most common side effect while your body gets used to it.  That's the reason for the half dosage initially.

I believe trial dosage is 850 mg twice a day.  And yes, as Timothy suggested, you start out lower to get the intestinal tract used to it. 

There are hundreds of clinical trials currently underway with thousands of breast cancer patients.  You cannot be diabetic to qualify for the trial.  Metformin does not usually cause blood sugar lows and that is why it can be given safely to non-diabetics.  Otherwise, the patients in the clinical studies would be at risk of serious hypoglycemia which can cause death if untreated.  Needless to say, I doubt there would be any clinical studies if Metformin cause low blood sugar. 

I am diabetic and started taking metformin (500 mg) many years ago.  In June 2010, after breast cancer was found and because my glucose levels were running a bit high, I went up to 2000 mg (1000 twice a day).  I may go back down to the clinical study dosage when I next see my PCP in a few months.  My only side effect, ever, is "loose stools."

Kaara and thatslife,

I don't think doctors are too hesitant in this case to put patients on it since the drug has a long history that shows a lot about what patients might be risky to put on it, and because the drug is inexpensive.

But the important thing here is to identify as sharply as possible how beneficial it is (or not) with breast cancer so that everyone has good information to know for sure it works as well as it is hoped it does. Getting good participation in the trials (whether one ends up on a placebo or on metformin) is very important because this IS one of the investigations that is actually likely to provide something generally nontoxic as a genuine weapon against cancer.

They need to have enough participation to find out if there are certain groups that get no benefit, or even are at a disadvantage, with the use of the drug even though they think it helps in general.

I proposed metformin as a possible solution in 2009 without knowing at the time that trials were just beginning that year. I was suggesting it for the increasing problem posed by weight gain that results from menopause. My thinking on that is that they were being so shortsighted in terms of early stage bc. They were giving therapy that caused early stage bc patients to become postmenopausal, and then ignoring the fact that putting them there increased weight gain which then increased the patients' risks again -- and they were ignoring that increased risk factor and patting themselves on the back for the short-term "saving" of lives.

So we really do need to prove conclusively how much benefit metformin provides. I just hope they are also paying attention to the data and just which patients do benefit, because it may not be as beneficial, for example, for those who are not postmenpausal -- and it would be a shame if they concluded that the benefit was not there with metformin in for bc patients in general without understanding that certain groups actually were benefitting. It is possible that it may be that patients who are younger get less benefit because they are not as likely to be postmenopausal.

I hope that explanation is worded well enough to make sense.

A.A.

AA:  With all due respect.  Screw the trial.  I am 28 and If any of my doctors think I am going to risk being put on a placebo when there is tons of information about the possible benefits of metformin they are INSANE.  I am 28 and stage 3 and I have many years I have to be around to watch my son grow.  I already have to give up having more kids, why the hell would I take a placebo when the potential benefit is there with very few side effects.  I have a significan science background so I understand and respect where you are coming from, but for me, its not worth it.  Why do you think SO MANY PCP are ok with prescribing metformin, including mine.  I haven't started it yet, but I was almost offended by my oncs approach asking me to be in the trial.  I know all women with BC deserve the chance and all women's cancers are different, but really in this I am all about myself on.  I have donated tissue and blood and urine and all sorts of things to tissue marker studys, but drugs and placebos are where I draw the line.  For instance the trial with avastin.  one leg of the trial is JUST TC, which is not a 3rd gen drug for stage 3ers, I'm sorry but I am not going to get put in the section with less chemo than I need just to see the potential benefits of the drug avastin.  Not going to happen.  Sorry for the rant, I and totally understand your explanation, but I think there are much better ways to do this than randomized placebos.  Some women maybe ok with being on the placebo end, not me...

minimacsmom:  You go girl!  I totally agree with your position.  When it comes to getting bc out of your life it really is all about you!  I'm 71 and blessed to have had a great life before bc, but getting it at 28 truly sucks!  I pray that you see your children and your grandchildren grow into productive adults, just as I have been able to do.

Keep the faith! 

bobkat:  That would be a question that you should definitely discuss with your doctor.  All the information I read had that cautionary statement.  Lactic acidosis can occur and it is life threatening.

so lactic acidosis ONLY in the setting of abnormal kiney function? 

starella:  The cautionary info also said that people with liver problems should not use Metformin.

When I went for my first app't with my MO and asked him about Metformin, he blew it off and said it wouldn't help me.  The reasons he gave were ridiculous...I don't have diabetes, I'm not overweight, and so on....none of that has anything to do with how the drug works.  He lost credibility with me after he made those statements, so I will be looking for another MO. 

I just e-mailed my MO about this - I told her I want to discuss it when i come in for Herceptin in 2 weeks.  

I spoke to my holistic physician and he is not keen on prescribing it for me for two reasons.

1)  It is a prescription drug and has notable SE's

2)  My circulating tumor cell test was negative, so there is no cancer in my body at this time.

He said there were too many good supplements on the market that prevent bc recurrence and do not have any SE's. 

I have been on it awhile...can't frankly remember how long. Perhaps memory loss is one of the side effects, lol. BUT, it's the only one I experience. I take 500mg 2x a day.

The drug has been in use for decades with great results and minimal se's. For me, it's a no brainer. Good point about the liver though. Perhaps at my next onc visit I will get them to check liver function. That little sucker has been through enough of a ringer.

Oh gracious!! Not shooting the messenger at all! I love having all the different opinions of docs and patients alike!!

This is one that I have spent a lot of time reading every study abstract I can get my hands on. I do wish it was more tested specifically with breast cancer..but for now, it seems like a good choice for me. Long term use on chemo treated patients...well, that's a little scary to think about. Statins are another area that are showing promise...but you have to wonder if I take A and then add B...am I throwing the system out of whack? Who knows what happens to the mechanisms of action.

 Another drug that my naturopath highly recommends for bc is low dose naltrexone. I haven't used it. Studies look good though.

It is tough finding docs you like to work with...I think I finally have a bit of a team. My naturopath, integrative md, and my onc. They all know about each other and I am open now about what I take...didn't use to be that way. I did high dose nutritional iv's throughout chemo and my onc went nutso about it. I continued them having done my research and feeling comfortable it was the right choice for me.

My MO is not impressed with the metformin studies.  He has been very impressed with the Zometa studies.  In fact he put me on a oral biophosanated about 6 months ago because fo the studies.  Now that the study has been compete he is putting me on Zometa.  My insurance abroved it.  He stays up on all the new studies but just was not impressed with this one.

hello

just found this discussion

i was just at Dana Farber monday for a 2nd opinion and the onc I spoke to said she would consider any high risk bc patients for the metformin trials

i didn't know this was being used until i found this thread

very interesting