  A sample of 1.3 mm continuum cores in the Dragon infrared dark cloud (also
known as G28.37+0.07 or G28.34+0.06) is analyzed statistically. Based on their
association with molecular outflows, the sample is divided into protostellar
and starless cores. Statistical tests suggest that the protostellar cores are
more massive than the starless cores, even after temperature and opacity biases
are accounted for. We suggest that the mass difference indicates core mass
growth since their formation. The mass growth implies that massive star
formation may not have to start with massive prestellar cores, depending on the
core mass growth rate. Its impact on the relation between core mass function
and stellar initial mass function is to be further explored.
