Left side rib pain is not always an early sign of cancer. In case of left side rib pain, it is generally considered to be caused by many reasons, such as rib injury, pleurisy, shingles, gastroesophageal reflux, pneumothorax or angina, etc. It may also be caused by cancerous diseases, such as breast cancer, lung cancer, kidney cancer or prostate cancer. Therefore, left side rib pain is not necessarily an early sign of cancer, and it is necessary to go to regular hospitals for detailed examination to make a clear diagnosis. If left side rib pain is caused by early stage cancer, there will be various uncomfortable symptoms, such as obvious pain, accompanied by fever or body wasting, etc. So, left side rib pain is not necessarily an early sign of cancer, it needs to go to regular hospital for detailed examination to make a clear diagnosis. Therefore, if you have left side rib pain, you can go to regular hospitals and cooperate with doctors to improve chest radiographs, chest CT, three-dimensional reconstruction of ribs and other examinations to judge and analyze, and then treat the cause in time after clarifying it.