Sorry to hear you are going through this.  Im in a similar position - my husband was diagnoed with Stage 4 RCC in December 2014, in August last year, it spread to his pelvis, in the acetabulum - which is the cup in which the ball of the femur sits.  The first indication was extreme pain, as the tumour had penetrated the nerve sheath and was inflaming the sciatic nerve.  He had a short hospital stay of around 10 days to stabilise the pain issues - radiotherapy was discussed but not taken up at the time.  He came out of hospital on crutches and has managed until now, quite well - we have some other issues going on now, but thats a nother story!  There are several good drugs available to help your husband, and as long as he gets his pain medication right and balanced with anti-emetics, laxatives etc theres no reason why he wont manage admirably. :)