Continuous and inexplicable loss of weight. A loss of weight is one of the most common indicators of cancer. It is also an exceedingly visible symptom. There are many plausible reasons for such a loss of weight, one being a disruption in the natural production of hormones. Another reason simply could be a lack of appetite due to a tumor in some part of the digestive passage, possibly the stomach. American cancer researchers say that it is crucial to get yourself tested for possible cancers if your weight inexplicably drops some by some ten or fifteen pounds. Throat cancer is also certainly known to cause loss of weight.