Spotting between periods can mean lots of things and not all of them mean cancer. When is the last time you have had a PAP done? Regular PAP's can help detect the presence of abnormal cells.
Spotting can be caused by a hormonal imbalance or a thyroid problem. If you are close to menopause or going through pre-menopause, then hormone fluctuations can cause spotting. Weight gain or loss can also affect your hormones.
Stress can be another factor that can cause spotting. It's always a good idea to plan a visit to the doctor when you have frequent bouts of spotting. Infections inside the vagina can cause spotting as well as fibroids and cysts, usually benign. If you have concerns about spotting - please call your doctor. It's the best way to put your mind at ease.