Radiation therapy uses high-energy radiation to shrink tumors and kill cancer cells (1). X-rays, gamma rays, and charged particles are types of radiation used for cancer treatment.
1 Lymph nodes of the armpit and neck may also be involved. 2  Viral infections such as infectious mononucleosis may affect the whole body and cause generalized lymph node swelling in various parts of the body, such as neck, armpit or groin.
Quick Answer. Underarm lymph node swelling caused by an infection or other illness can also cause pain, according to WebMD. Lymph nodes located in the groin, behind the ears, at the back of the head or under the jaw may also swell.