[Bobby Parmar] (0:00 – 1:52)
Why are we spreading all this misinformation about women’s health? Then we leave women to their pain. We leave them to their hemorrhagic bleeding.
We leave them to anemia. We leave them to all these awful things they don’t need to be suffering from — because there’s literally a solution right in front of you.
That’s why it’s so important to stop saying things like, “You’re going to get breast cancer because of this,” or “You’re going to get a tumor because of this,” or “Don’t take hormones, they’re going to cause all these problems.”
Hi, Off the Charts.
It’s me, Bobby Parmar. I’m so excited to talk to you about estrogen today. We’re going to go over a lot of what I think has created confusion.
No matter how many influencers are out there trying to “set the record straight” — whether they think estrogen is evil or estrogen is an angel (depending on whichever part of their conscience is talking to their brain) — I want to explain the actual context so you understand how we got here, why we think the way we do, and so you feel more confident about this topic.
We’re going to cover a number of things related to one major concern people have about estrogen: breast cancer.
It really helps to understand what estrogen does, so we’re going to talk a lot about the risks of estrogen on breast cancer — and the specific scenarios that might apply to you:
• having babies
• whether you breastfed
• if you didn’t have babies
• if you have an IUD
• if you’re on birth control
• if you’re not on birth control
• if you have a family history of breast cancer
I’m going to try to cover everything, and hopefully this gives you a solid understanding of what this is all about.
Okay — so let’s start with some common scenarios you might be dealing with in your own life.
Scenario number one…
[Paige] (1:53 – 1:56)
So does estrogen actually cause breast cancer?
[Bobby Parmar] (1:57 – 4:47)
Okay — this one’s really important. Thanks for asking.
Estrogen plays two very different roles in our lives.
Estrogen exposure from inside your body — the estrogen you make when you’re ovulating, the estrogen produced in your tissues, the estrogen converted from other hormones — that lifetime exposure increases breast cancer risk.
The longer you’re exposed to your own estrogen, the more chances estrogen has to mutate breast cells and make them divide. And when cells divide, errors happen — that’s essentially what cancer is: a mutation error. Lots of things can trigger that error.
So yes, lifetime exposure to your own estrogen is a real, established risk factor.
There’s no debate about that.
But here’s where people get confused.
A lot of people online say, “Stop blaming estrogen, estrogen is totally fine!” — and what they’re actually talking about is prescribed estrogen.
That’s different.
When you give estrogen to someone who is in perimenopause or menopause, you’re not giving them anywhere near the amount they used to make naturally for decades. Especially when they’ve stopped ovulating and aren’t producing their own estrogen anymore.
Here’s the key difference:
When estrogen was causing those potential mutations earlier in life, it was because it was constant and high. But when a person reaches menopause and estrogen levels drop to almost nothing — a desert of estrogen — giving estrogen back actually does the opposite.
It becomes protective.
It actually reduces breast cancer risk in menopausal women. I know — it seems like a puzzle. But it’s real.
• Estrogen earlier in life: ↑ increases risk
• Estrogen after menopause (replacement): ↓ decreases risk
It’s a paradox. But the data is extremely clear:
Estrogen-only therapy after menopause reduces breast cancer risk by about 22–23%.
That’s huge.
You are not going to get breast cancer from menopausal estrogen replacement.
That’s not the same thing as the lifetime exposure your own body created for decades.
That’s the difference.
[Paige] (4:47 – 4:53)
Wait, what? So our own estrogen is the problem? Like… poison?
[Bobby Parmar] (4:53 – 5:52)
Yeah — so, okay, here’s the thing.
You’re not poisoning yourself. We shouldn’t treat estrogen like some dark, villainous, toxic thing. Estrogen is wonderful. It does so many amazing things:
• prevents osteoporosis
• helps prevent dementia
• reduces colon cancer risk
• protects muscle
• supports mood, metabolism, and more
It’s basically the fountain of youth — we just don’t call it that for other reasons.
But for breast tissue, it’s different. Over time, breast tissue is like, “Okay, enough. You’ve been poking at me for decades.”
Those constant “pokes” create small changes — inflammation, cell turnover, tiny mutations — that can eventually lead to tumors.
That’s the difference.
We shouldn’t call estrogen bad.
But yes, our own lifetime estrogen exposure is a risk factor for breast cancer.
[Paige] (5:52 – 5:55)
So does breast size matter for breast cancer?
[Bobby Parmar] (5:56 – 5:59)
No. This is another really interesting thing.
[Paige] (5:59 – 5:59)
Okay.
[Bobby Parmar] (5:59 – 8:39)
So the size of your breasts doesn’t matter here. Having more breast tissue doesn’t automatically mean you’re going to have a higher risk of breast disease.
It’s density.
Density isn’t size.
You can’t feel density.
You can’t grab your boobs and be like, “Oh, they feel dense today.” There’s no way to squeeze them and think, “They’re riper this time of the month,” or anything like that. Density can’t be felt — it has to be seen on an X-ray.
When you get a mammogram, they’ll tell you your BI-RADS density category:
A, B, C, or D.
C and D are dense.
You cannot feel that. You can’t press it. You can’t guess it. You just don’t know.
Everything else — size, shape — none of that affects breast cancer risk.
It is density that matters, because the denser the tissue:
The easier it is for tumors to hide on imaging
Dense tissue itself is more biologically active and more prone to forming tumors
Dense tissue is dynamic. It has more of those inflammatory, rapidly changing qualities that can contribute to cancer. Size is irrelevant — density is the factor.
Okay ladies, look at this graph. This is what we’re going to reference when we talk about different things that happen throughout your life and how they affect your overall risk.
I just mentioned density — and you can see right here that women with dense breasts have a 2 to 4 times higher risk of breast cancer.
It says:
• 26% or more of the breast being dense = higher risk
• 11–25% dense = lower risk
That’s a big deal.
So next time you get a mammogram, make sure you check your density.
A lot of my patients don’t even know. Every day I ask women, “What’s your letter?” and they say, “Letter? What letter?”
I mean your density letter.
I’m not sure how universal this is across countries, but here in Canada, women should be told whether they are A, B, C, or D. C and D are more dense.
And if you’re in the more dense categories, you may need more frequent follow-up — maybe yearly mammograms, or ultrasounds on top of that, so the tumors aren’t hiding in the density.
[Paige] (8:40 – 8:44)
Okay, I have a question. Can density actually change as you get older?
[Bobby Parmar] (8:45 – 10:00)
Yes. Paige, thank you for this wonderful question.
Density changes over time as your hormones change.
As you go through menopause, your breasts become more fatty, so density decreases. That’s why it’s easier to detect cancers in postmenopausal breasts — there’s less “white” on the mammogram, so things stand out more.
You can also technically increase density again — not something we usually want, but it can happen.
If you put someone on hormone therapy (estrogen plus progesterone), their density can increase slightly.
For example, if you had around 60 cm² of dense tissue, hormones might increase it by another 5–10 cm².
So women on hormones still need good monitoring, because increased density can make imaging a bit harder to interpret.
But naturally, after menopause, that 60 might drop to 30 or 40. It can go down by half.
But women never feel that difference. You can’t feel density — it’s invisible without imaging.
[Paige] (10:01 – 10:04)
And what about alcohol? Does it really raise breast cancer risk?
[Bobby Parmar] (10:05 – 13:39)
You can see on our chart that it does. Alcohol increases breast cancer risk by about 1–2 fold.
And we need to talk about this honestly.
A lot of women are going sober right now — not because of addiction, but because they’re realizing alcohol affects their hormones, mood, sleep, and overall wellbeing. They just feel better without it.
But that doesn’t mean you have to stop drinking.
It just means there’s a relative increase in risk.
And honestly, it’s similar to the difference between eating a couple extra small fries from McDonald’s every week. These are relative risks; we need to frame them so people can decide what’s meaningful to them.
If you have multiple risk factors —
• family history (mom, grandmother)
• genetic predispositions
• very dense breasts
• past biopsies
• atypical breast findings
• long lifetime estrogen exposure (early puberty + late menopause)
— then alcohol might become a more significant risk enhancer for you.
There’s a great way to explain this.
Last year I was a guest on a podcast and one of my quotes went viral — like 4–5 million views — because it sounded controversial. I said that smoking a bunch of cigarettes is equivalent to drinking a couple glasses of wine per week.
People freaked out.
So let me clarify.
There’s a study comparing the cancer risk of alcohol vs tobacco, and it shows the number of cigarettes per week that have an equivalent cancer risk to one bottle of wine per week.
A bottle of wine per week is about 4 glasses. In terms of breast cancer risk, that’s equal to 80 cigarettes per week.
Not lung cancer, not mortality — for breast cancer specifically, alcohol has a unique effect on breast tissue that matches that level of risk.
The study says:
“If 1,000 women each drank one bottle of wine per week, eight women would develop breast cancer as a result.”
You may hear that and think, “Only eight in a thousand? Not a big deal.”
And for many women, that’s totally fine — enjoy your rosé.
But for other women, eight in a thousand feels too high.
And they get to decide that.
The key is being honest about the numbers.
[Bobby Parmar] (13:44 – 14:20)
Probably not. It’s likely all alcohol. Alcohol is technically a carcinogen — technically.
But remember, that just means it has the ability to contribute to cancer, even if the risk is very, very low. Lots of things are carcinogens:
• the sun
• fried foods
• even everyday environmental exposures
So alcohol isn’t unique in that sense.
It’s not about wine versus hard liquor versus beer. Alcohol itself is the issue. Researchers often study wine simply because it’s the most commonly consumed drink among women in these studies.
[Paige] (14:20 – 14:27)
Interesting. So if you already have high estrogen exposure or dense breasts, does alcohol make it worse?
[Bobby Parmar] (14:28 – 14:48)
Yes, it makes it worse for those groups. If you have dense breasts, high lifetime estrogen exposure, and you’re also drinking a bottle of wine or more per week, now you’re stacking risks. You’re building an Eiffel Tower of risk, so to speak — each factor adding on top of the others.
[Paige] (14:48 – 14:51)
So if someone stops drinking, does the risk go down?
[Bobby Parmar] (14:52 – 15:24)
If you stop drinking alcohol, absolutely the risk goes down.
Would there already be some damage done? Yes, girl — we can’t take back the past or erase every exposure. But it still helps.
Quitting gives your tissue a break. It stops the chronic exposure and allows the body to repair what it can. And there are things that can support that repair process — maybe that’s a whole other podcast episode, but not for today.
[Paige] (15:25 – 15:28)
Taller women are more at risk. I didn’t even know that.
[Bobby Parmar] (15:28 – 16:49)
I know — shocker to the taller ladies, the Nicole Kidmans of the world. But yes, height is a risk factor.
If you’re about five inches taller than the average woman, you have roughly a 30% higher risk of breast cancer compared to shorter women.
Why?
Because the hormones that trigger growth spurts — things like growth hormone and IGF-1 (insulin-like growth factor) — also stimulate cell growth in general. And anything that drives rapid growth can, in theory, contribute to tumor growth over time.
It doesn’t mean tall women need to panic or wish they were shorter. It’s simply one additive risk factor.
A taller woman who also has dense breasts or other risk factors might just need to be more diligent about not skipping mammograms for six years. That’s all.
[Paige] (16:49 – 16:54)
And is that just for breast cancer, or does height affect other cancers too?
[Bobby Parmar] (16:55 – 17:44)
Height is associated with higher risks for several conditions. We see it clearly in diseases like acromegaly — where excess growth hormone dramatically increases tumor risks. Height itself isn’t a disease, obviously, but the biological pathways involved in growth can influence cancer risks.
And there are strange associations. For example, there’s a type of “hot tub pneumonia” that tall, thin women get more often. It’s believed the same biological traits that made them tall and lean also affect their lung structure, making them more susceptible to certain bacterial infections.
So yes, height plays a role in various conditions.
[Paige] (17:45 – 17:48)
Does childhood nutrition play a role in this?
[Bobby Parmar] (17:48 – 18:29)
Nutrition absolutely matters — but it’s nuanced.
Good childhood nutrition helps you grow, and growth is healthy. But the hormones that fuel that growth may also influence long-term cancer risk.
It’s a balance.
There’s no perfect design. Being 6’2” doesn’t mean you’ll avoid disease forever. No, girl — that’s not how biology works.
[Paige] (18:30 – 18:36)
So let’s talk pregnancy. Ooh — so the age you have your first baby really affects risk.
[Bobby Parmar] (18:36 – 21:32)
This one is dramatic, and people often react strongly to it.
Yes — the age at which you have your first baby is a built-in risk factor in the major breast cancer calculators.
Here’s where it gets controversial:
If you have your first baby after around age 25 (some studies say closer to 30), your risk of breast cancer is slightly higher compared to women who had their first child earlier.
In medicine, pregnancies over 35 are called “geriatric pregnancies” — awful term, extremely outdated, but it technically refers to “advanced maternal age.” After 35, there are more pregnancy-related and postpartum risks.
But for breast cancer specifically, the threshold for risk appears earlier — around 25 to maybe 30.
So women ask:
“OMG, I had my first baby at 27 — am I doomed?”
No. No. No. That’s not what it means.
It means your relative risk is 1–2× higher than baseline — not that something terrible will happen.
Why?
Because before age 25, your breast cells undergo full differentiation during pregnancy. They mature into these robust, stable cells that are resistant to mutating.
After around 25, cells don’t complete that same differentiation process. They’re a bit more vulnerable to DNA errors.
Add to that:
• pregnancy causes big estrogen surges
• estrogen surges can increase DNA damage in aging cells
So the older you are for your first pregnancy after ~25, the more this risk gradually increases.
Again — this does NOT mean don’t have babies. Have your babies!
It just means:
If someone had their first baby at 35…
and maybe had several babies after that…
and has dense breasts…
maybe some biopsies…
family history…
— that woman needs to be extra diligent about breast exams and mammograms. That’s the whole point.
[Paige] (21:33 – 21:38)
But what about women who’ve never had kids? How does that affect the risk?
[Bobby Parmar] (21:39 – 23:26)
Women who never have children — we call that nulliparity — are an important group when it comes to breast cancer risk.
And when you think about it, it kind of makes sense.
If you never have a pregnancy, you never get that break from ovulation and estrogen. No pregnancy, no breastfeeding break — we’ll talk about breastfeeding in a second.
So you’re:
ovulating continuously
producing lots of estrogen
never getting that reset that pregnancy and breastfeeding can bring
You also miss out on the protective effect that early pregnancy has on breast tissue when it happens before about age 25. Without pregnancy, breast tissue doesn’t go through the same degree of maturation.
A lot of women will tell you they feel like a different person after having a baby — and physiologically, that’s true. Your receptors change, your hormone patterns change, your periods often change.
Some women who had bad endometriosis, really heavy periods, or terrible pain find that after pregnancy, their periods become much more manageable or even normal. That’s that big hormonal reset we’re talking about — it can “downregulate” some of the proliferative, mutant cell activity in the breast tissue.
When you don’t have children, you don’t get that reset.
Again, this is not a reason to go have kids. It’s simply one of the factors we plug into risk calculators.
So yes, nulliparity — never having had a baby — is another factor that increases breast cancer risk.
[Paige] (23:27 – 23:30)
And breastfeeding, does that lower the risk?
[Bobby Parmar] (23:31 – 23:53)
Yes. This one is kind of magical.
As a person who will never breastfeed, it blows my mind for a lot of reasons.
From a breast cancer perspective, you have to ask: does breastfeeding increase risk or lower it? What would you think?
[Paige] (23:54 – 24:05)
I mean, I feel like it has to have an impact, right? Your body goes through so many changes to make milk. But I’m not sure if that makes the risk higher or lower.
[Bobby Parmar] (24:06 – 25:25)
Great. Let’s clarify this milky situation — it’s so milky.
When you’re breastfeeding, you’re producing all kinds of other hormones:
prolactin
steroid hormones
insulin and others
They all surge toward the breast tissue. At the same time, there is destruction and remodeling of lobular (alveolar) breast tissue — which kind of “crowds out” room for estrogen.
Remember earlier I said that lifetime exposure to your own estrogen is a risk factor for breast cancer?
Breastfeeding provides a break:
a break from ovulating and producing high estrogen
and a break because other hormones dominate the breast tissue environment
All those milk-making hormones make it harder for estrogen to “live” there.
So:
fewer ovulatory cycles
less estrogen stimulation
and local breast tissue that is temporarily inhospitable to estrogen
Estrogen basically “doesn’t go here” while breastfeeding — and if it can’t set up shop, it can’t have the same mutating effects locally. That’s why breastfeeding is associated with a lower risk of breast cancer.
[Paige] (25:27 – 25:29)
And what about the women who can’t breastfeed?
[Bobby Parmar] (25:29 – 26:09)
Of course, there are many women who aren’t able to breastfeed.
Remember: these risks and protections are relative, not absolute.
If you didn’t breastfeed, it does not mean you’re going to get breast cancer. It just means your risk is about 1–2 times higher than someone who did breastfeed, all else being equal.
We have to let the math math. These factors are additive — they stack.
So if “not breastfeeding” is a checkmark on your list, that just means:
you should be on top of mammograms
we should pay attention to your breast health
we should put your information into a risk calculator and see where you land overall
It’s about understanding your personal risk picture, not panicking.
[Paige] (26:11 – 26:15)
What about IVF? Does that change anything for breast cancer risk?
[Bobby Parmar] (26:15 – 30:08)
No. There’s no known increased breast cancer risk from IVF itself — meaning from the high-dose fertility hormones and procedures.
The exception is if the underlying reason you needed IVF is part of a disease process that also increases cancer risk on its own. In that case, it’s the condition, not the IVF protocols, that’s linked to cancer.
The IVF itself is not considered a primary risk factor.
Now, let’s talk about other hormone exposures — birth control and IUDs — because so many women ask about these.
Okay you guys, there’s so much confusion here. So many women ask:
“Do IUDs, hormonal IUDs, or birth control pills cause breast cancer?”
Let’s start with IUDs.
IUDs are getting such a bad rap lately and I honestly don’t know why. I think someone ran with a headline or a single article and it just spread.
In reality, hormonal IUDs are very safe. They:
prevent a ton of pain
prevent unwanted pregnancies
are incredibly effective
I think they’re wonderful. Full disclosure: I own an IUD clinic, so yes, I’m biased — but I’m biased because I see every day how helpful they are.
Now, breast cancer risk:
Putting in an IUD — does it increase your risk?
Overall, no meaningful increase has been shown. There was a Danish study a few years ago that found a tiny increase: 14 cases per 10,000 women.
That’s 0.14% — still very small. (The original AI transcript said 0.014%, but 14 in 10,000 is 0.14%.)
Think about it this way:
We would never say, “Don’t cross the street, there’s a 0.14% chance of getting hit by a bus.” That would sound ridiculous.
But headlines love numbers like this and they scare people.
There’s also a bias in these studies:
Women who choose IUDs tend to:
see their doctors more
be more proactive about their health
get more exams and tests
And when you see doctors more, you’re more likely to have things found — including cancers. So part of that small increase may simply be better detection, not that the IUD is causing cancer.
So the true risk is likely even lower — possibly negligible.
Oral birth control pills are very similar.
There’s no major increase in breast cancer risk, and there are many benefits:
lower risk of ovarian cancer
lower risk of endometrial cancer
pregnancy prevention
So the overall risk-benefit profile is strongly in favor of using them when needed. The breast cancer risk doesn’t outweigh those benefits and is, again, very small.
[Paige] (30:09 – 30:15)
So with a hormonal IUD, how does that affect breast tissue when it’s working mostly inside the uterus?
[Bobby Parmar] (30:16 – 31:40)
Fabulous question, Paige.
If the hormone in the IUD stayed completely inside the uterus, then why do some women experience mood changes, acne, low mood, or headaches in the first few months?
It’s because a small amount of the hormone does enter the bloodstream. With levonorgestrel IUDs (like Mirena), maybe around 1% of the hormone goes systemic.
There are also lower-dose IUDs for people who are more sensitive or who don’t want to lose their periods altogether. Depending on the device, about 30–50% of people will stop getting a period, which tells us the hormone is doing something beyond just sitting in the uterus.
So yes, a little bit gets into the body, hits receptors, and can cause side effects — usually temporarily. Most people adjust and the symptoms fade.
But for some, the side effects persist, and that’s very real. So a small portion of the IUD hormone does affect the whole body, including potentially breast tissue — but again, the overall breast cancer risk remains very low.
[Paige] (31:40 – 31:54)
Honestly, I think a lot of women are just scared because we hear so much misinformation about IUDs or even contraceptives. Like, people say they’re harmful, or risky, or poisonous. So it’s really hard to know what’s real.
[Bobby Parmar] (31:55 – 33:52)
My God — Mary, take the wheel. IUDs are not poisonous.
Yes, like birth control, they can cause side effects. Yes, they can change your breast density a bit at first and then it usually settles. Yes, insertion can be very painful if you’re not offered proper pain control.
But overall, they do not cause the level of harm that people on the internet are fear-mongering about. They are not the devil.
It doesn’t make sense that in an era where we supposedly value truth, we’re spreading this much misinformation about women’s health.
Because what happens when we do that?
We leave women:
in pain
with hemorrhagic bleeding
anemic
suffering through things they do not need to be suffering through
All while a solution is literally right in front of them.
That’s why it’s so important not to say things like:
“You’re going to get breast cancer because of this.”
“You’re going to get a tumor.”
“You should never take hormones.”
We’re talking today about lifetime exposure to estrogen — the estrogen your body makes over decades.
In another episode, we’re going to talk specifically about what happens when you take estrogen as therapy. I’ve already told you: menopausal estrogen therapy doesn’t cause breast cancer — in fact, it reduces it.
But just wait until we go deep into HRT, MHT, whatever acronym you use, and its effects on cancers and overall health. That’s going to be a good one — it’s coming up soon.
Thank you so much for joining me today. I really had a great time and I hope you did too.
Please share this with a friend — or a lot of friends — and leave me a review. It really helps promote this podcast.
Thanks so much.
