In general, the safety rules for patients suffering from advanced, metastatic cancer, whose disease has proved refractory to existing drugs and other therapies (eg radiotherapy, surgery), can be laxer because, to put it grimly, they are so ‘up against it’ that they are prepared to take the risks of an experimental drug – even one with such horror stories and horrendous reputation as thalidomide has.

(of course, the very qualities that resulted in such terrible birth defects – suppression of growth – are exactly those that cancer patients want for their tumours!)

one must consider the risks and benefits of the particular drug. If s/he has high benefit (bad cancer nonresponding to other drugs), but low risk (probably not many people with cancer are pregnant, rigth? And even if so, what’s the chance of giving birth to such a kid?), s/he may be willing to take that risk and take that drug…

Thalidomide is a drug used in the treatment of leprosy. In the late 1950s, thalidomide was prescribed to expectant mothers to treat morning sickness, anxiety, and insomnia. A decade later, the Food and Drug Administration took the drug off the market after more than 10,000 babies exposed to thalidomide in the womb were born with severe adverse thalidomide birth defects including serious malformations and limb deformities. Types of birth defects caused by include:

Missing limbs
Phocomelia – Absence of majority of arm, with hand extending from shoulder
Aplasia – Absence of thumb and bone in lower arm
Lower extremity limb malformation
Ear and vision malformation
Heart birth defects
Kidney malformation
Genital malformation
Digestive tract and nervous system impairment

Source:thalidomide birth defects

FDA is not "lax" – all drugs have contraindications. The Agency uses all those criteria in approving drugs – including cautions as to use by certain groups. Obviously, application by women of child bearing age would be one here. It is the responsbility of the prescrivbing physician to address these.

If it is the difference of life and death, and there is little or no chance of doing harm to a fetus there is absolutely no reason to not take the drug. We should not be held back from substances that might save our lives because of events of the past.