Sepkowitz KA. Opportunistic infections in patients with and patients without Acquired Immunodeficiency Syndrome. Clin Infect Dis. 2002 Apr 15;34(8):1098-107. Epub 2002 Mar 21.
Table 1 summarizes incidence of PCP in cancer patients - data taken from 3 studies
1.3% of patients with solid tumors while receiving glucocorticosteroids
Also, a Cochrane Review, Prophylaxis for Pneumocystis pneumonia (PCP) in non-HIV immunocompromised patients (2007), states that the incidence of PCP in non-HIV patients is increasing, naming cancer patients treated with corticosteroids as one of the at risk groups. (See Background section of the review)