When you use the actual numbers of people, you get those numbers by using the base rate: 10,000 women total, of which 100 have cancer (that’s the base rate in action), of which 80 test positive, etc. So if you use the numbers 80 (= 0.8 0.01 10000) and 950 = (0.096 0.99 10000), you’re not ignoring the base rate. You would be ignoring the base rate if you used the numbers 8000 and 960 (80% and 9.6% of the population of 10,000, respectively), but those numbers don’t refer to any relevant groups of people.
When you use the actual numbers of people, you get those numbers by using the base rate: 10,000 women total, of which 100 have cancer (that’s the base rate in action), of which 80 test positive, etc. So if you use the numbers 80 (= 0.8 0.01 10000) and 950 = (0.096 0.99 10000), you’re not ignoring the base rate. You would be ignoring the base rate if you used the numbers 8000 and 960 (80% and 9.6% of the population of 10,000, respectively), but those numbers don’t refer to any relevant groups of people.