Nana, this time of year it isn't uncommon for roses to send out long 'octopus' arms/stems. I think our cooler wetter weather has encouraged it even more. I usually just prune the stems back to the length of the rest of the stems so it doesn't look out of proportion. I don't like to cut it all the way back, because the foliage on those stems are great food factories for the rose, photosynthesizing up a storm to help get the rose through winter. Besides, you may get some very nice blooms on those stems! Enjoy.

Compare the stem and foliage of this new growth to the stems and foliage of the older growth.
It is likely that they will not match.

If that is the case, the new growth is rootstock (in the U.S., that would likely be 'Dr. Huey,' a vigorous once-blooming climber.)

You can compare the leaves of your new growth, also, to images on HelpMeFind. Click on the PHOTOS tag.

Here is a link that might be useful: Dr. Huey on HMF

If you determine they are not root stock but the original variety, wait until they bud and bloom before cutting them back. You may as well enjoy a flower. Pruning back can promote more canes and blooms but it's getting late in the season so an early frost could destroy late blooms.

I agree, let them bloom. If they don't bloom, that would suggest they are rootstock suckers. These suckers come from beneath the graft swelling and need to be ripped out at the point of origin, rather than being pruned, which would lead to regrowth.

If these are first-year plants, at some point in their development young plants naturally start producing shoots stronger than the early ones. Some HTs can produce 5-6' shoots; however, most varieties do not.