BACKGROUND:

Carcinoma of unknown primary (CUP) of the pelvis is a challenging entity for the oncologist. The role of human papilloma virus (HPV)/p16 in carcinogenesis and prognosis is more established in the head and neck than in the pelvis. In the case of an HPV positive occult primary of the pelvis the radiation therapy target coverage is not well established.

CASE REPORTS:

Case#1: A 69-year-old female with a left retroperitoneal and pelvic mass was treated with chemoradiation to a dose of 45 Gy in 25 fractions to elective lymph node regions and simultaneous boost to FDG-avid lymph nodes to 55 Gy in 25 fractions. A post-treatment PET-CT showed complete response of disease now 7 months post treatment. Case#2: A 58-year-old female with a large left retroperitoneal pelvic mass was treated post-operatively with chemoradiation to 45 Gy in 25 fractions with a pelvic boost to 54 Gy. She is clinically and radiographically with no evidence of disease at 4 years. Case#3: A 47-year-old female with left sided retroperitoneal pelvic mass that declined therapy. She ultimately died of progressive disease at 1 year after diagnosis.

CONCLUSION:

Cisplatin based chemoradiation is effective for treating HPV/p16 + pelvic squamous cell cancers of unknown primary as long as the mass, regional lymph nodes and high risk pelvic primary sites are adequately covered.