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.
Other serious causes of painful lymph nodes in the groin include the following: 1  Testicular cancer. 2  Lymphoma. 3  Infected Lymph Node (Lymphadenitis) 4  Cancer in the pelvic area or lower extremities. 5  Hernia. 6  Lipomas (Fatty growths)