Can A Pregnancy Test Detect Cancer?

I recently came across a post circulating online that stopped me mid-scroll. 

It sounds wild, but it is a question that has been quietly popping up in fertility and TTC circles. Can a simple home pregnancy test really pick up cancer?

What Pregnancy Tests Actually Detect 

Every pregnancy test,  whether it’s digital or a strip test, detects human chorionic gonadotropin (hCG), a hormone your body produces during pregnancy. It’s made by the placenta once a fertilised egg implants in the uterus.

But here’s the interesting part: hCG isn’t only made during pregnancy. According to the National Cancer Institute, some cancers can produce hCG too, especially rare ones called germ cell tumours. These can develop in the ovaries or testes, and in very unusual cases, certain stomach, lung, or liver cancers may also release hCG. That’s why in hospitals, doctors sometimes check hCG levels when investigating certain tumours.

Why You Might See a Faint Positive

If you’ve ever seen a faint line that seems to appear and disappear, there are several much more common explanations, and they’re usually harmless.

1. Chemical Pregnancy: a very early pregnancy that ends soon after implantation. It can briefly raise hCG levels before they drop again. Read more on early miscarriage here 
2. Test Sensitivity: Some brands detect incredibly tiny amounts of hCG, as low as 6 mIU/mL. That means you might see a faint line at night when your urine’s more concentrated, but nothing in the morning.
3. Evaporation Lines: If you check the test after the recommended time window, a faint line can appear. It’s not a real positive. Hoopsy has a guide on common evaporation line questions here
4. Hormonal Changes: People going through perimenopause or with conditions like PCOS can have naturally low levels of hCG that a sensitive test might pick up. 

When hCG Might Point To Something Else

In very rare cases, germ cell tumours or choriocarcinoma (a type of cancer linked to pregnancy tissue) can produce hCG. This happens when tumour cells mimic placental tissue.

However, these cancers are extremely uncommon and almost always come with other symptoms, like abdominal pain, swelling, or unusual bleeding. A faint positive on a home test, by itself, is not a likely sign of cancer. If your GP suspects something unusual, they’ll order a quantitative blood test to measure exact hCG levels and follow up with imaging if needed.

Should We Be Concerned?

It’s natural to find this worrying. The idea that a pregnancy test could detect cancer sounds like something out of a health thriller –  but the truth is far more measured. While a few cancers can produce hCG, doctors don’t consider home pregnancy tests a reliable indicator of anything other than pregnancy.

For clinicians, this overlap is well-known and accounted for with specific lab tests. The concern isn’t that cancer is hiding in plain sight – it’s that hormones are complex, and tests can sometimes give confusing results. That’s why open discussions like these matter: they help people understand why something odd might happen, and when it’s worth seeking medical advice.

Bottom Line 

So, can a pregnancy test detect cancer? 

Technically, yes – but only in very rare situations!

For most people, a faint line or inconsistent result is due to timing, hormone fluctuations, or the sensitivity of the test. While some cancers do produce hormones, a pregnancy test is not a reliable screening method.

If you’re not pregnant but keep getting a positive result, don’t panic – just see your GP for clarity and peace of mind. A pregnancy test is designed to detect pregnancy, not disease. But sometimes, your body’s chemistry blurs the lines (literally). Getting answers is always better than guessing.