  The Noether Symmetry Approach can be used to construct spherically symmetric
solutions in $f({\cal R})$ gravity. Specifically, the Noether conserved
quantity is related to the gravitational mass and a gravitational radius that
reduces to the Schwarzschild radius in the limit $f({\cal R})\rightarrow {\cal
R}$. We show that it is possible to construct the $M-R$ relation for neutron
stars depending on the Noether conserved quantity and the associated
gravitational radius. This approach enables the recovery of extreme massive
stars that could not be stable in the standard Tolman-Oppenheimer-Volkoff based
on General Relativity. Examples are given for some power law $f({\cal R})$
gravity models.
