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The math of invasive breast cancer risk for LCIS
Lobular Cacrinoma in Situ (LCIS) confers a risk of invasive breast cancer of about 2% a year, maybe a little less, when chemoprovention endocrine meds are NOT taken. If meds are taken, the risk is cut in about half, maybe even cut a little more, so 1% or less.
Furthermore, LCIS is a lifetime risk. That means any 40 year old woman diagnosed with LCIS who could expect to live until 85 has a lifetime risk of 2%/year x 45 more years of life = 90% lifetime risk of cancer. Let's say the risk is only 1.5% per year, to be wildly optimistic and not 2%, since some studies have indicated the annual risk is less than 2%. Then that comes out to a 67.5% lifetime risk, still a big number. (1.5%/year x 45 more years of life)
Other sources show a lifetime risk of developing invasive breast cancer with LCIS to be 20% with some showing up to 35%. Those results do not come out to 2%/year for most women, unless the diagnosis is made at around 65 years or older.
Examples: Age 65 at diagnosis with life expectancy of 85 years means if using even the lower 1.5%/year risk, it is 1.5%/year x 20 more years of life = 30% lifetime risk. Age 70 at diagnosis with life expectancy of 85 years, again using the 1.5% figure is 1.5%/year x 15 more years = 22.5% lifetime risk.
Even the halved annual risk of 1% over a lifetime that may be obtained by taking chemoprovention endocrine meds still does not add up to a halved 10%-18% (instead of 20%- 35%) life time risk of invasive breast cancer,
Example: LCIS diagnosis at age 40 with life expectancy of 85. 1%/year x 45 years to reach age 85 = 45% lifetime risk. While better than even odds for a 40-year old, I think many women would consider something that close to 50% of getting cancer to be too high, especially after investing 5-10+ years of taking risk-reducing drugs, which produce substantial side effects for many. But a diagnosis at age 55 with a 1% annual risk due to medications, would result in a 30% lifetime risk, if life expectancy was 85. (1%/year x 30 years = 30%)
Interestingly, I have repeatedly seen that of all the LCIS diagnoses, only 10%-20% are in women past menopause, so using ages 55-75 for examples to make the annual risk come out similar as lifetime risk does not reflect the reality of who has the most cases of LCIS. I have also read that the number of post-menopause LCIS cases, though now a minority, is growing. And I am one.
Some of us have high hopes of making it to 90+ if we've had many relatives who have lived that long, so that means that 2%/year (or the more optimistic 1.5% or even the 1% with drugs) really makes lifetime risk soar upward.
For women diagnosed in their 30s, or younger, those 2%s accumulate over an even longer period, so that the odds of invasive cancer could easily reach 100% over a lifetime. Or more, but of course that is not possible. However, no studies I have found warn of guaranteed invasive breast cancer (100%) for those with LCIS if you live long enough.
Something does not add up. Perhaps it is the mathematician, (me). Or my LCIS assumptions are wrong. Maybe risk does not increase in a linear fashion year after year, maybe it tapers off? It seems to me that either all the lifetime risk numbers out there from reputable sources are wrong or the 2%/year over a lifetime (halved or more with medication) is wrong. So that those of us with LCIS can decide what treatment is best, we need to know which numbers are right--and which are wrong.
Can the Mayo experts or the moderator or another poster shed some light? Thank you in advance.
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That was impressive. Personally for me just based on how the diagnosis has changed back and forth over the years from pre cancer to benign to “increased risk”. This was enough for me to make the decision of pbm. With that said I am not a good candidate for tamoxifen since I have RA to begin with. I did read somewhere that up to 40% are unable to stay on tamoxifen due to side affects. As others have said it’s not an easy decision either way. Now I am faced with the decision of implants or diep flap with the latest news on implants. Another scary decision. This is a journey even without a cancer diagnosis. Prayers to all of us faces with this decision on how to proceed.
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4 Reactions@amy11559, have you had your pbm already? May I ask what age your diagnosis was?
My surgery is this week. I am 50 yrs old. I am scheduled for nspbm with expanders. I hope to do ok and I hope to have DIEP at some point in the next few months. I am honestly terrified but this past year when An enhanced 6 cm nodular nonmass was found on my mri I felt a total loss of control. This was only two months after having a biopsy that showed a benign fibroadeonoma on the other breast. The fear that went through me that week was worse. I felt betrayed after having mammos and Sonos every year and doing everything I was suppose to do. I always felt we as woman were in control by having our yearly mammograms. This year I found that lobular hyperplasia and chances doesn’t always show up on imaging and that mad me angry. One one of three surgeons agreed to remove the fiboadenoma along with the nonmass on the opposite side. That is where the alh was found
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4 ReactionsTried anastrozole, side effects were so bad I had to stop taking it , I did not do well with no estrogen and I know I would not live to 90 and I am 64 now . It is a slow growing cancer , they said they got it all and i did 30 rads . This is also a chemo drug and I would have been on it 10
Years . Don’t let fear control your treatment
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3 ReactionsThank you for your experiences and responses, @cancersucks and @amy11559. Amy, you decided to do the DIEP at a later date then your nspbm, why did you choose that instead of getting it all done at once, may I ask? Best of luck with your surgery and I understand you may not be checking online forums and responding for a while with your upcoming schedule, @amy11559.
Hi. Thank you for your well wishes. The plastic surgeon did not think I was a good candidate for one procedure. I was originally upset but he explained why and the more I thought about it I felt so overwhelmed making the decision of what I wanted anyway (silicone, saline or DIEP). I felt a sense of relief not having to make that decision yet. The ps said since I am larger chested that does not make me a good candidate for direct implant. Also in February I had a bilateral lumpectomy with reconstruction and he felt putting a heavy implant at the time of the mastectomy would jeopardize the blood supply to the breast. I spoke to many woman who have been through this and was surprised to find that several have reconstruction the same way. It’s called immediate reconstruction but not direct.
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3 Reactions@elsie37
Thanks for your additional info, @amy11559. The time frame seems very appropriate for your situation. I have thought about the timing as well and wondered if doing the operations separately would be less taxing on the body. That seems to be the case for you--and for the other women you spoke to.
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1 ReactionBut I am still wondering, how one set of facts regarding LCIS, based on National Center for Biotechnology Information (NCBI) research, can provide a risk of invasive breast cancer of 50%, 60%, 70% over a lifetime (when 2%/year is given) and other reputable sites like American Cancer Society state 20% to maybe 35% lifetime risk? Without accurate information, we cannot make decisions. And 20% compared to 70% is a huge discrepancy.
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4 ReactionsCompletely agree. My alh pathology was an accidental finding at age 50. How do I know this hasn’t been there for 15 years. How can I get a 20 percent chance over 5-15 years of being discovered. Very unsettling
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