Tamoxifen for 5% ER?

[bejuce]

My pathology showed that I'm 5 % ER+. Is this enough for considering Tamoxifen to be added to my treatment plan? What is the threshold?

Thanks!!!

Marcia

[Jackie07]

Marcia,

I think mine was also just 5% ER. I know, it sounds so tiny, but that's how ER+ is determined. Hope the information below helps:

The first molecular target for targeted cancer therapy was the cellular receptor for the female sex hormone estrogen, which many breast cancers require for growth. When estrogen binds to the estrogen receptor (ER) inside cells, the resulting hormone-receptor complex activates the expression of specific genes, including genes involved in cell growth and proliferation.

Research has shown that interfering with estrogen’s ability to stimulate the growth of breast cancer cells that have these receptors (ER-positive breast cancer cells) is an effective treatment approach.

Several drugs that interfere with estrogen binding to the ER have been approved by the FDA for the treatment of ER-positive breast cancer. Drugs called selective estrogen receptor modulators (SERMs), including tamoxifen and toremifene (Fareston®), bind to the ER and prevent estrogen binding. Another drug, fulvestrant (Faslodex®), binds to the ER and promotes its destruction, thereby reducing ER levels inside cells.

Another class of targeted drugs that interfere with estrogen’s ability to promote the growth of ER-positive breast cancers is called aromatase inhibitors (AIs). The enzyme aromatase is necessary to produce estrogen in the body. Blocking the activity of aromatase lowers estrogen levels and inhibits the growth of cancers that need estrogen to grow. AIs are used mostly in women who have reached menopause because the ovaries of premenopausal women can produce enough aromatase to override the inhibition. Three AIs have been approved by the FDA for the treatment of ER-positive breast cancer: Anastrozole (Arimidex®), exemestane (Aromasin®), and letrozole (Femara®).


www.cancer.gov/cancertopics/factsheet/Therapy/targeted

National Cancer Institute.

[Jackie07]

From Cancer.org:

Hormone therapy is another form of systemic therapy. Like chemotherapy, hormone therapy can be used either as an adjuvant therapy to help reduce the risk of cancer recurrence after surgery or when the cancer has become metastatic.

Some breast cancers grow in response to the hormone estrogen. Estrogen is usually thought of as a "female" hormone, but men have it in their bodies as well, just at lower levels. About 9 out of 10 breast cancers in men have hormone receptors on the surface of their cells -- that is, their cancers are estrogen receptor (ER)-positive and/or progesterone receptor (PR)-positive. This makes them more likely to respond to hormone treatments. Hormone therapy does not help patients whose tumors are both ER- and PR-negative.

Several approaches to blocking the effects of estrogen or lowering estrogen levels are used to treat breast cancer in women. While many of these may work in men as well, doctors have the most experience with using anti-estrogen drugs such as tamoxifen in men.
In the metastatic setting, hormonal treatments are often used in a sequence. For example, tamoxifen may be tried first. If the cancer does not respond or if it grows back after an initial response, other hormonal treatments may be tried.

Tamoxifen: Tamoxifen works by blocking the estrogen receptors on cancer cells, which prevents estrogen from spurring their growth. It is taken daily in pill form, usually for 5 years, to reduce the chances of the cancer coming back after surgery. Tamoxifen can also be used to treat advanced breast cancer.

The most common side effects include fatigue, hot flashes, and sexual problems. A rare but more serious side effect is blood clots, which usually form in deep veins of the leg. In some cases, this increased risk of clotting may lead to a heart attack, stroke, or blood clots spreading to the lungs (pulmonary embolism). Call your doctor or nurse right away if you develop pain, redness, or swelling in your lower leg (calf), shortness of breath, chest pain, sudden severe headache, confusion, or trouble speaking or moving.

Aromatase inhibitors: This group of drugs includes anastrozole (Arimidex), letrozole (Femara), and exemestane (Aromasin). They block the production of small amounts of estrogen by the adrenal glands. They are taken daily as pills. They have been found to be very effective in treating breast cancer in women, but they have not been well studied in men. Still, some doctors use them as the first line of hormone therapy instead of tamoxifen. Clinical trials are also under way to look at using aromatase inhibitors along with LHRH analogs (see below).

The main side effects of these drugs are thinning of the bones and joint stiffness.

[suzan w]

good question! I was told to be glad (ha!!) that my cancer was ER+ because at least I had a weapon to use...for me, Arimidex, having gone through menopause. xo Suzan

[Debbie L.]

Marcia, did you have your ER re-checked when you transferred care to Stanford? That's a borderline level and it could actually be negative, so that you could avoid enduring the side effects of a drug that has nothing to offer you.

Forgive me if I've asked this question of you before. I did look through your posts and don't see double-checking mentioned.

Unfortunately and upsettingly, ERPR levels are often inaccurate when done at local labs and if the results are borderline, that can be a crucial error. It doesn't matter if, for example, the error is between 60% positive and 80% positive. But when we get close to zero, it matters. I had mine redone at Baylor and both ER and PR were negative. Local lab had said 5% ER+ and for that I got two years of Arimidex. It's easy to get a second opinion pathology from Baylor, using your slides and tumor blocks from the initial surgery or biopsy. But if you're now receiving care at Stanford, they should be able to do it there. Or maybe they already have?

If it's reliable report of 5% ER+, then it's muddier. Current thinking is that it's possible that any degree of ER positivity could benefit from endocrine treatment. However, at least with Tamoxifen (and it's probably the same for AI's), response to endocrine therapy improves as ER levels rise. Some oncs will tell those will low ER+ pathology that it's worth trying the endocrine therapy but that if side effects are really troublesome, they would not push a woman with a low ER+ cancer to continue the endocrine therapy (because it probably offers her a small benefit).

What is Stanford telling you about how much benefit you can expect from Tamoxifen?

Debbie Laxague

[mts]

Marcia,

I posed this same question a few years ago... I too am 5% ER+ and PR neg.
I spoke to a pathologist from MD ANderson Texas-- and she told me that samples sent from the operating table to the lab to be frozen can lose some viability and therefore a 5% result may actually be higher... I had my ER checked 3 times... one in Florida, a second opinion that was sent to MD Anderson and a 3rd sample that was sent to UPenn... all came back different (but all ranges between 5% and 15%.

I was on tamoxifen for approx 5 months at first, and I really could not tolerate it. People told me that side-effects -in essence - was proof that the tamoxifen "was working".
My onc has gone back and forth on this with me since 2005... He has told me time and again that a little ER+ is still positive and that although the benefits may not be as great as someone who has a higher ER, its still a benefit...
I have not been on Tamoxifen for nearly 3 years and feel great. I know I must sound like a wimp- especially since there are so many women who would prefer to have Tamoxifen side effects vs. chemo... but I truly felt awful taking the tamoxifen (vertigo like side effects). Although I am reminded of my bc every time I look in the mirror, I don't have the Tamoxifen thing sitting on my shoulder. I am comfortable living with my ounce of doubt. I am now 5 years post diagnosis... been through it all and feel at peace with my decision.

In the end, its what ever you can live with. Both physically and mentally.

Maria

[flynny]

I too am ER+ 5%. I originally had my path report done in a "Local Lab" in Manchester, NH but then my mother's on who then became my onc at Dana Farber had 3 doctors test my slides and it came back 5%. She was very particular about my case because my mother was dying of mets when I was dx.

We are just a VERY small group of women that this happens to. Aren't we special! I believe that we will benefit regardless if it were only 2%.