There's a long-format story at the BE Story Club called "Hollywood Hills". In the story, aging movie star Holly Wayland approaches a shady doctor about restoring her youth. The drug he gives her has an unexpected effect:
The rest of her body was transformed simultaneously. Holly felt the cellulite in her
thighs melt away, as if she was undergoing liposuction. A similar effect happened
around her midsection. Her abs started to peek through as her belly fat slowly began
to melt away. She didn’t have much before, but she wasn’t in the absolute pinnacle of
physical fitness either. Age had taken its toll. Holly was beginning to see herself like
she once did more than 10 years ago… as a fit and attractive 30-something. She
looked great and the changes were continuing.
Her breasts, already riding high from two previous breast enhancement surgeries,
firmed up even more and started to gain mass. Holly was a little worried. She weighed
in at a healthy D-cup before the changes started, but as she watched they filled out to
at least an F-cup. Her breasts were surging outward with a vengeance, seeming overly
anxious to grow. Holly realized she’d need to get her implants taken out after the
changes were through. Her body had finally given her what she never had naturally,
an impressive bustline.
With the continued expansion, Holly began to worry more than a little. The growth
in her breasts was not stopping, much less slowing down. She felt her skin stretch and
pull as her boobs pushed outwards. Holly quickly unfastened her bra before it had the
chance to snap off, which it surely would have done had she not taken action.
Impressively, there were no stretch marks to accompany this rapid growth. Her skin
was growing right along with her breasts, accommodating her expanse. By the time
the growth leveled off, her breasts were the size of volleyballs. She looked enormous.
Written by Anonymoose, there are six full-page illustrations by PortalComic accompanying "Hollywood Hills". The full story is available to BE Story Club subscribers.