Objects of the class tt(TumorInfo) provide access to the following paramters:
tt(Beir7, Growth, Incidence) and tt(Survival), which are covered in the
following sections.

In addition its member tt(cumTotalRisk) computes the cumulative total risk,
given the radiationrisk as determined in tt(Loop::caseInit). For each case the
(Incidence) carrier is randomly determined given the probabilites of the
various carriers. 

The cumulative total risks over all ages are computed by subsequently adding
the products of the risk of getting a tumor (given the selected carrier) times
the radiation risk (for the used age).

