Interraction

[CathyVI]

Am working on this practice learning model: I have a data that can be used to estimate the effects of two genes on cancer incidence.  Assume these data were obtained from a large prospective cohort study.  It can be assumed that the sample was taken from a genetically homogenous population and thus confounding is not an issue. How can I present the evidence for interaction as suggested by Knol and VandeWeele (2012) in table form. First, I thought about creating a dummy variable in sas but I don't know the code for interaction for a dichotomous variable.

This is my sample data:

ID	GeneA	GeneB	Cancer
1	0	1	1
2	0	0	1
3	0	0	0
4	0	0	0
5	0	1	0
6	0	0	0
7	0	0	0
8	0	0	0
9	0	0	1
10	0	1	0
11	1	0	0
12	0	0	0
13	0	1	0
14	1	0	0
15	1	0	0
16	0	0	0
17	0	1	0
18	0	1	0
19	1	1	1

[StatDave]

Interactions in a modeling procedure are indicated with an asterisk. For example:
class genea geneb;
model cancer = genea geneb genea*geneb;