  Very recent inelastic $\alpha$-scattering data on the isoscalar monopole and
dipole strength distributions in $^{56}$Fe, $^{58}$Ni, and $^{60}$Ni are
analyzed in the relativistic quasiparticle random-phase approximation (RQRPA)
with the DD-ME2 effective nuclear interaction (nuclear matter compression
modulus K$_{nm}= 251$ MeV). In all three nuclei the calculation nicely
reproduces the observed asymmetric shapes of the monopole strength, and the
bimodal structure of the dipole strength distributions. The calculated centroid
and mean energies are in very good qualitative agreement with the experimental
values both for the monopole, and for the low- and high-energy components of
the dipole transition strengths. It is noted, however, that while DD-ME2
reproduces in detail the excitation energies of the giant monopole resonances
(GMR) in nuclei with $A \ge 90$, the theoretical centroids are systematically
above the experimental values in lighter nuclei with $A \leq 60$. The latter
can be reproduced with an effective interaction with a lower value of K$_{nm}
\approx $ 230 MeV but, because of the asymmetric shapes and pronounced
fragmentation of the monopole strength distributions, isoscalar GMR data in
light nuclei cannot provide accurate estimates of the nuclear matter
compression modulus.
