Substitution of Alimta/Carboplatin for Alimta/Cisplatin

In reviewing the scientific evidence for substituting Carboplatin for Cisplatin it appears that there is very little difference in response rate and survival.   Why do oncologists persist in using Cisplatin as first line? It is data driven.  Cisplatin/Alimta was a randomized placebo controlled trial that compared Alimta/Cisplatin to Cisplatin plus placebo.  In this trial 456 patients participated and a survival advantage was proved over cisplatin alone.  Trials have reported similar results by using the combination of Carboplatin Alimta but the number of patients participating was less and the trials were not randomized. This makes a comparison of the trials to be less than optimal, but there is enough data to say the results appear comparable.  This being said, most oncologists will recommend the combination that has the most data and the best designed trial and the largest number of patients which in this case would be Alimta/Cisplatin.  This being said there are many characteristics of a patient that are considered when recommending Carboplatin rather than cisplatin.  When we measure patient’s kidney function we do an equation that requires age, weight, sex, and creatinine level.  This calculation gives us an estimate of a patient’s renal function.  The older the patient the more likely they are to have diminished function.  We assess for functional hearing loss, sometimes involving a referral to an audiologist.  Does the patient have diabetes, and related neuropathy.   Does the patient require medications that are competitive for renal clearance that cannot be changed?  When kidney function is borderline, consideration is given to the number of cycles that can be safely given before an impact on kidney would be expected.

Toxicities associated with Cisplatin are hearing loss, kidney damage, delayed nausea and vomiting, and peripheral neuropathies.  In contrast Carboplatin dose is calculated based on a patient’s kidney function so we can adjust for those who have prior kidney damage.  Nausea and vomiting is less severe and is not associated with delayed onset nausea.  Carboplatin has less neuropathy associated with its use. There is more myelosupression associated with Carboplatin and this can result in a low white blood count, anemia and low platelets.  Patient often require transfusion after repeated cycles of drug and treatments are often delayed while awaiting recovery to safe treating levels. Rarely does Carboplatin affect hearing.

Your oncologist will make the recommendation of which regimen best suits your particular needs and as often is the case if a patient has been responding nicely to Alimta cisplatin and then evidences a change in kidney function or other toxicities more closely associated with cisplatin they may at this point substitute Carboplatin for Cisplatin

~Mary Hesdorffer, NP