The words ‘roller-coaster ride’ get thrown around a lot when talking about shares. But there are roller coasters and then there is Angle (LSE: AGL). This penny stock is more like a bucking bronco! In early 2024, it surged more than 100% in a single day, then lost half its value in a month. Now the share price has risen by 79% in four weeks to sit at 21p. But it’s still 78% lower than it was just two years ago. I have a very small position in the stock. Should I add to it? AIM-listed Angle is a cancer diagnostic company that has developed a potentially groundbreaking technology called the Parsortix system. This provides a unique approach to capturing and analysing circulating tumour cells (CTCs) from the blood of cancer patients. The system appears to represent a significant advancement in liquid biopsy (a blood test that allows the detection and analysis of cancer cells or fragments of the tumor’s DNA). Cancer treatment often relies on understanding the specific characteristics of a patient’s tumour. Yet these can change over time. So the ability to capture CTCs and analyse them effectively allows the monitoring of cancer patients’ responses to treatments. This...