On Thursday, Taylor Swift posted a heart-breaking note about her mum, who she revealed has been diagnosed with cancer. In the note, Taylor writes that after urging her healthy-seeming mum to visit the doctor for a routine check on her health, the results from cancer tests she had came back positive. Taylor didn't specify what cancer her mum has, so it's impossible to know what kind of test she had in order to be diagnosed or if her mum told her doctor of any symptoms that led to more tests. In fact, there's no blanket way to check for every cancer, so it's possible that Taylor's mum either showed symptoms that alerted her doctor or showed abnormal levels of something in her body after getting blood drawn for a complete blood count (CBC), which measures the amounts of certain cells in your blood. While routine blood tests like a CBC are informative, they will only give you a snapshot of your health; having too few or too many of certain cells can be caused by many reasons, so a general blood test is not a definitive way to check if you have cancer. While you can't just make an appointment and ask for a general cancer test, Taylor's note is a good reminder that having a regular relationship with your primary doctor (or even gynaecologist) will help her keep track of your health so she can order tests for anything out of the ordinary. If your doctor does suspect something abnormal, there are specific blood tests that can detect possible tumour cells or other abnormalities in your blood. Scheduling regular physicals and being sure to make all your cancer screenings — like a Pap smear every two to three years to screen for cervical cancer and a clinical breast exam or mammogram to screen for breast cancer — are also smart ways to take control of your health and do what's best for your body. Check out our list of tests, check-ups, and cancer screenings you should be doing in your 20s and 30s.