Lower chest pain with pnemonia is sign of lung cancer?

Not necessarily: You can get chest pain from pleurisy associated with the pneumonia. That would be the most common cause for chest pain, together with muscle sprain from coughing. Of course, if you are concerned about cancer, get checked!

Not first thought: While chest pain can be a symptom of lung cancer, pain is often more common in pneumonia then lung cancer. Later stage lung cancers may cause pain, but unfortunately lung cancer may remain hidden for years. If you are being followed/treated for pneumonia, speak with your physician to assess your current status/progress.